What is your favorite way to eat a marshmallow? Melted in hot chocolate after a long day of sledding? Or roasted and squished between a slab of chocolate and graham crackers while you are sitting around a campfire? However you like them, marshmallows are an unusual type of sweet treat — spongy, sticky and a little bit chewy, with a melting point that is just a bit above body temperature, so that they start to change from a solid to more liquid state as soon as they reach the warmth of your mouth, or the warmth of your hot chocolate or campfire!

They are also an ancient creation, originally coming from a tall marshmallow plant (Althaea officinalis) that grows in swampy fields and has a soft, spongy root. The root contains mucilage, a thick, gluey substance produced by some plants and microscopic animals to help with seed germination and water and food storage. Some cultures used the marshmallow plant to make candy, while others used it to make medicine. The ancient Egyptians, for example, dried the root and mixed it with honey to make marshmallow treats, but the early French thought the root looked like lung tissue, and experimented with making medicine out of its gummy juice to soothe sore throats.

Today’s modern marshmallows contain no parts of the marshmallow plant though, because the plant is considered a medicinal herb. Instead, modern marshmallows are primarily a mix of three ingredients: sugar, corn syrup and gelatin, with the gelatin replacing the thick, gluey substance from the marshmallow plant.

The sugar and corn syrup are heated together with a little water to make a solution. The solution is warmed and brought to a boil, turning it into syrup. The sugar in the solution makes the boiling point of the solution higher than the boiling point of pure liquid water, which is 100° Celsius (212° Fahrenheit). The greater the concentration of sugar in a solution, the higher its boiling point. As the solution boils, water evaporates, the solution becomes even more concentrated with sugar and the boiling point gets pushed even higher. For example, an 85 percent sugar solution has a boiling point about 16 degrees C (28 degrees F) higher than the boiling point of pure water.

The final concentration of sugar in the syrup determines the structure of the candy that forms when the syrup cools. Think about the difference between the texture of caramels and lollipops — the caramel is softer and chewier, while the lollipop is hard and cracks when it is bitten. The syrup used to make caramels is cooked until it reaches 115–120 °C (240–250 °F), at which point it has an 87 percent concentration of sugar in solution and enters the firm ball stage (see the Exploratorium link in the Bibliography for more information about this). The syrup used to make lollipops, though, is cooked until it reaches a 99 percent concentration of sugar in solution at a temperature of 150–155 °C (300–310 °F), which makes drops of the syrup turn into hard, brittle, easy-to-break threads when placed in cold water.

When making marshmallows, the syrup is cooked until it reaches 112–115 °C (235–240 °F) or 85 percent concentration of sugar in solution, and corn syrup is added to the solution to help prevent crystals from forming in the cooled syrup. Nobody likes crunchy marshmallows!

So, where does the gelatin come in, and just what is gelatin anyway? Gelatin is that wiggly, jiggly food that seems almost magical as it suspends fruits, forms shapes and sculptures and transforms from a solid to a liquid as soon as it hits the warmth of your mouth. It is not magic, but special gelatin molecules are responsible for these food tricks.

Gelatin comes from collagen, the main protein in connective tissue, which is a specialized, fibrous tissue in animals that connects other tissues together, like tendons connect muscles to bone. The special quality of gelatin is that it is a protein that can coagulate (or come together) when it is beaten or whipped. So, to make marshmallows, hot concentrated syrup is beaten into gelatin with a mixer. The beating process forms bubbles in the syrup and protein mixture, and the gelatin coagulates at the point where the air in the bubble and the syrup-protein mixture meet, stabilizing the bubble walls so they don’t collapse.

In this cooking and food science fair project, you will make your own gooey marshmallows, using different amounts of sugar and corn syrup to find out which ratio of sugar to corn syrup makes the best-tasting and best-textured treat.

Experimental procedure

Preparing to cook

1. Wash your hands.
2. Get out all cooking tools and ingredients and set them out so they are ready to go and easy to access.
3. Identify the 116 °C mark (240 °F) on your candy thermometer. This is the traditional temperature used to make marshmallows.

Preparing your cake pans

1. Label the bottoms of three cake pans with masking tape pieces, numbered 1 to 3. Pan 1 will contain recipe 1, pan 2 will contain recipe 2, and pan 3 will contain recipe 3. Each recipe contains a different ratio of sugar to corn syrup.
2. Pour a small amount of vegetable oil on a paper towel and lightly oil the three cake pans.
3. Pour a small amount of powdered (confectioner’s) sugar in the strainer and dust the inside of the cake pans.
   1. If you get too much powdered sugar in the pan, hold the pan upside-down over a sink, and gently tap out the excess.

Preparing your gelatin

1. Pour 40 mL (1/6 cup) of cold water into the large mixing bowl.
   1. To get 1/6 cup, fill the 1/3 measuring cup halfway with water.
2. Sprinkle one 1/4-ounce (oz) envelope of plain, unflavored gelatin over the cold water.
3. Mix the gelatin and water together for about 5 seconds (sec) with a fork and set the bowl aside. This will give the gelatin time to “soften” or “bloom,” as shown in Figure 1 below.

Preparing your syrup

1. Add 60 mL (1/4 cup) of cold water to the saucepan.
2. Using Table 1 below as a guide, add granulated sugar and corn syrup to the water in the saucepan, according to which recipe you are currently making. This step is shown in Figure 2 below.

Ingredients	Recipe 1	Recipe 2	Recipe 3
Sugar	120 mL (1/2 cup)	160 mL (2/3 cup)	180 mL (3/4 cup)
Corn syrup	80 mL (1/3 cup)	60 mL (1/4 cup)	40 mL (1/6 cup)
Ratio of sugar to corn syrup	3:2 (1/2:1/3)	8:3 (2/3:1/4)	9:2 (3/4:1/6)
Ratio, written as a decimal	1.5	2.7	4.5

3. Put the lid on the saucepan. An adult should closely supervise all work from this point on.
4. Turn on the stove to medium-high heat.
5. Lift the lid and check the solution in the saucepan about every 30 sec until it just comes to a boil.
6. Remove the lid and set it aside.
7. Begin to measure the temperature of the syrup in the saucepan using the candy thermometer.
   1. When using the thermometer, do not let the tip of the thermometer touch the bottom or sides of the pan. Instead, try to put the tip below the surface, closer to the middle of the pan.
8. Continue heating your syrup solution until the temperature reaches 116 °C (240 °F).
   1. WARNING: The syrup will be very hot, so use extreme caution when working around the pan.
   2. Observe how the temperature rises. Does it go up quickly at first? What happens as the solution becomes more concentrated? Record your observations in your lab notebook.
9. When the temperature reaches 116 °C (240 °F), immediately turn off the stove and move to the next section, Making Your Marshmallows.

Making your marshmallows

1. Turn the mixer on low and carefully pour the hot syrup solution into the gelatin and water in the large mixing bowl, as shown in Figure 3 below.
   1. Note: Some syrup solution will likely solidify on the saucepan as the syrup cools. However, if you pour too slowly, or wait too long and do not immediately pour the syrup into the bowl after turning off the stove, you may end up with a lot of syrup solidified on the saucepan, which may affect your results.

2. Set the timer for 11 minutes and start it.
3. Gradually increase the speed of the mixer until it is operating at full (high) speed, as shown in Figure 4 below.

4. Continue to beat for approximately 11 minutes, or until the mixture starts to become very thick, glossy and lukewarm.
5. Add 2.5 mL (1/2 teaspoon) of vanilla, as shown in Figure 5 below, and beat for another minute.
   1. Write down the total time that you beat the recipe in your lab notebook.
   2. Try to beat each recipe for approximately the same amount of time.

6. Pour a thin layer of vegetable oil on a spatula and scoop out the marshmallow mixture from the mixing bowl and into the prepared cake pan with the masking tape piece that matches the recipe number.
7. Use the spatula to gently smooth down the top of the marshmallow, so that it is pretty flat.
   1. If the top of the marshmallow mixture naturally smooths itself down when you put it in the pan, or if the mixture is so sticky that it is very difficult to smooth it down with the oiled spatula, skip this step.
8. Wash and dry all cooking utensils.
9. Repeat the sections Preparing Your Gelatin, Preparing Your Syrup and Making Your Marshmallows two more times with clean materials, until all three recipes have been prepared, as shown in Figure 6 below.
   1. To have the best control over all the variables you should make all three recipes on the same day. Otherwise, uncontrollable variables (like the humidity on that day) may affect your results.
10. Repeat the entire Experimental Procedure (up to this point) two more times so that you have a total of three trials (pans) for each recipe. Repeating the recipes makes sure that your test results are accurate and repeatable.
    1. You can do this step on a different day if you would like.

11. Allow the three marshmallow “pies” to sit out, uncovered, on a counter for at least 4 hours, or up to overnight, so that they become firm.

Preparing your marshmallows for testing

1. Once the marshmallow pies have become firm, after at least 4 hours or overnight, turn the pans over, one at a time, onto a cutting board.
   1. If the marshmallow sticks to the bottom of the pan, push on the bottom of the pan a bit, or use a spatula to help lift it out.
2. Roll a pizza cutter in some powdered sugar, and then use it to cut up your marshmallow into pieces that are about 3 centimeters (cm) by 3 cm (one inch by one inch). Use a ruler to help measure where to cut.
   1. An alternative to the pizza wheel is to use a small cookie cutter to cut out shapes.
3. Dust the marshmallows on all sides with a little powdered sugar, using the strainer.
4. Place the marshmallows in the air-tight container or plastic bag, being sure to label the container or bag with the recipe number and the trial number (remember, you will be performing three trials) from the masking tape pieces, so you know which recipe was used for each bag or container. The marshmallows will keep in an airtight container for up to a week, so you have around six days in which to make and test all the trials.

Testing your marshmallows

Perform the following three tests to investigate the melting temperature, the toughness and the taste of the marshmallows you made from each recipe. Perform each test one trial set at a time.

1. Melting tests: Drop three marshmallow pieces (one from each recipe) in a pan of hot water and see which piece melts first.
   1. Because of slight variations in marshmallow sizes, pick three pieces that are of the same size and shape.
   2. Start a timer and see which one melts first, second and last. Record your results in a data table in your lab notebook.
   3. Repeat the test at least three times per trial set to make sure your results are repeatable and accurate.
2. Cutting tests: See which marshmallow is the toughest using a cheese cutter, like the test described in the Science Buddies cooking and food science fair Project Idea Tough Beans (in the Procedure section titled “Testing Your Cooked Beans”). Alternatively, you can try an easier but less quantitative method using a small disposable cup, like a Dixie cup.
   1. If you use the disposable cup method, do the following:
      1. Put a marshmallow piece from one of the recipes on a cutting board.
      2. Arrange a small cookie cutter so that it can sit on top of the marshmallow. (You will need the cookie cutter to be thinner than the marshmallow pieces to do this.)
      3. On top of the cookie cutter, balance the small disposable cup.
      4. Put 20 pennies in the cup, one at a time.
      5. Remove the cup and cookie cutter from the marshmallow piece and inspect the marshmallow. Did the cookie cutter leave a noticeable impression? Use a camera to take a picture of the marshmallow piece.
      6. Repeat this process with marshmallow pieces from the other recipes. Eventually you will want to have repeated the test at least three times per trial set. Record your results in a data table in your lab notebook.
3. Taste tests: Gather your family and friends and give them three samples of marshmallows, one from each recipe in a trial set. Have them evaluate the samples for taste and texture.
   1. Which recipe do they think made the best-tasting samples? Which recipe do they think made the best-textured samples? Record your results in a data table in your lab notebook.
   2. Read this Science Buddies article about sample size to determine how many volunteers you will need.

Analyzing your results

1. For melting tests, average the results of your time tests from the three trials, and plot the decimal ratio of sugar to corn syrup on the x-axis, and the melting time on the y-axis.
   1. Do you see a correlation between the melting time and the ratio of sugar to corn syrup used? If so, why do you think this is? Hint: Re-read the introduction.
2. For cutting tests, if you used the protocol from the science project Tough Beans, average your coin counts from the three trials (to get a measure of the force required to cut through the marshmallow), and plot the decimal ratio of sugar to corn syrup on the x-axis, and coin counts (or cutting force) on the y-axis.
   1. If you used the small disposable cup method, print out the pictures you took and put them on your science project display board.
   2. Do you see a correlation between how tough the marshmallow pieces were and the ratio of sugar to corn syrup used? If so, why do you think this is?
3. For taste tests, make a bar chart showing the ratio of sugar to corn syrup on the x-axis, and the number of people who thought it had the best taste on the y-axis. Make a second bar chart showing the decimal ratio of sugar to corn syrup on the x-axis, and the number of people who thought it had the best texture on the y-axis.
   1. Why do you think some people preferred marshmallows made using one recipe compared to marshmallows made using another recipe? Were some pieces too sweet or too hard for your taste testers, or not sweet enough or too soft?

Variations

• Develop other ways to test your marshmallows. For example, measure the density of the marshmallows from each recipe, using a scale, graduated cylinder and Archimedes’ principle. Plot the ratio of the sugar to corn syrup on the x-axis and the density on the y-axis.
• Choose the recipe that has a decimal ratio of 2.7 for the sugar to corn syrup. Vary the final cooking temperature (deviate from the traditional 116 °C [240 °F]) to see how that affects the taste, texture, melting time, toughness and/or density. Be sure to conduct repeat trials at each temperature you test.
• Break up your taste-testing volunteers into male and female, or by age, to see if there are gender or age differences in marshmallow taste or texture preferences.

This activity is brought to you in partnership with Science Buddies. Find the original activity on the Science Buddies website.

The word forensic comes from the Latin word forensis, which means of or before the forum. “During the time of the Romans, a criminal charge meant presenting the case before a group of public individuals in the forum. Both the person accused of the crime and the accuser would give speeches based on their side of the story. The individual with the best argument and delivery would determine the outcome of the case. Basically, the person with the sharpest forensic skills would win. This origin is the source of the two modern usages of the word ‘forensic’ — as a form of legal evidence and as a category of public presentation.” (Wikipedia, 2008)

Today, the use of scientific evidence is so prevalent in the courtroom that the term forensics has become associated with forensic science. Forensic science is any science that is used in the courts or judicial system and it is extremely vital. The goal of a forensic scientist is to remain impartial and to appraise all of the available evidence in order to determine the truth.

Forensic science includes many areas of study, such as criminalistics, engineering science, pathology and biology. If a sports player were to die suddenly while playing a game, a forensic scientist with a specialty in pathology and biology would be called in to find out the cause. The scientist might have to perform an autopsy and examine the body to determine if the death had a natural cause — such as a health problem — or not. (To find out more about a related career, you can check out the Science Buddies career profile on pathologists.)

On the other hand, a forensic engineer may need to apply engineering principles to the purposes of law investigations. For example, a forensic scientist with specialty training as a civil engineer may study failure analysis and evaluate the quality of construction and manufacturing of structures involved in a crime or catastrophic event. They may look into why a particular car rolled over or why a building or bridge collapsed.

In general, to become a forensic scientist, you may need to study math, science and engineering. To find out more about being a forensic scientist, you can check out the Science Buddies career profile on forensic science technicians.

In this forensics science project, you will investigate how the size of blood spatter changes depending on the height that the blood was dropped from, but you will be using fake blood instead of real blood. In crime scenes where people are wounded, investigators apply principles of blood spatter analysis by taking measurements, such as of the diameter of the blood spatter, to figure out what happened. How do you think the diameter of the spatter changes as blood is dropped from different heights? Find out by trying your hand at collecting evidence in this science project and remember that solving mysteries is serious work!

Terms and concepts

• Forensic science
• Evidence
• Blood spatter analysis

Questions

• What is forensics?
• What are the different areas of study in forensic science?
• What kinds of projects do forensic scientists work on?
• How do you think the height from which something falls, such as a drop of blood, affects how it lands on the surface below?

Objective

To investigate how, in the field of forensic science, the size of blood spatter correlates to the distance from which the blood fell.

Resources

The following sources will help you learn more about forensic science:

• Wikipedia Contributors. (2014, March 24). Forensic science. Wikipedia: The Free Encyclopedia. Retrieved March 25, 2014.
• Wikipedia Contributors. (2014, March 22). Bloodstain pattern analysis. Wikipedia: The Free Encyclopedia. Retrieved March 25, 2014.
• Layton, J. (2008). How Crime Scene Investigation Works. Howstuffworks. Retrieved May 5, 2008.

Materials and equipment

• Digital scale (or you can use measuring spoons)
• Graduated cylinder, 50 mL or 100 mL size (or you can use measuring spoons)
• Cornstarch (17 g or about 2 tbsp)
• Corn syrup (60 mL or about 4 tbsp)
• Red food coloring (5 mL or 1 tsp)
• Bowl
• Water
• Fork or spoon for mixing
• Optional: Plastic wrap
• Cardboard. You will want enough cardboard to create seven pieces that are each about 30 cm by 30 cm (12 in by 12 in). The pieces should be able to lay flat and should not have many folds or creases in them.
• Scissors
• Pencil or pen
• Medicine dropper
• Measuring tape
• A chair or stepping stool
• Metric ruler or measuring tape that has millimeter marks
• A location to do your experiment where the ground can be easily cleaned (in case of spilling the simulated blood). For example, concrete or linoleum may work well.
• Optional: Butcher paper or newspaper
• Helper
• Lab notebook

Experimental procedure

Making the simulated blood

1. Using the digital scale, weigh 17 grams (g) of cornstarch and place it into the bowl. (Or measure two tablespoons [tbsp] of cornstarch and add it to the bowl.)
2. Thoroughly mix 30 milliliters (mL; 2 tbsp) of water into the cornstarch with a fork or spoon. The mixture must be smooth, as shown in Figure 1 below.

3. Add 60 mL (4 tbsp) of corn syrup to the bowl and mix thoroughly. The mixture should be smooth, as shown in Figure 2 below.

4. Mix in 5 mL (1 tsp) of red food coloring. Stir until the mixture is a consistent color, as shown in Figure 3 below.

5. You should now have a small bowl of simulated blood. If you will not be using it right away, cover the bowl with plastic wrap and set it aside.
6. Note: Be careful not to spill the simulated blood on furniture or carpeting, as it can stain! If it does spill, be sure to clean up the simulated blood immediately.

Blood spattering

1. Carefully cut up the cardboard into seven pieces of similar sizes. Each piece will be used for testing a different height.
   1. Each piece should be about 30 centimeters (cm) by 30 cm (12 inches [in] by 12 in). This will give you a good amount of space for dropping 10 drops of simulated blood onto each piece.
   2. Make sure the pieces can lay flat.
   3. Avoid using pieces with many folds or creases in them.
2. Use a pencil or pen to label each piece of cardboard with the height you will be testing on it.
   1. The heights you will be testing are 30 cm (12 in), 60 cm (24 in), 90 cm (36 in), 120 cm (48 in), 150 cm (60 in), 180 cm (72 in) and 210 cm (84 in).
3. Lay the cardboard piece you labeled for testing a height of 30 cm (12 in) flat on the ground where you will do your experiment.
   1. Because the simulated blood can stain, you should only do this experiment on a surface that can be easily cleaned, such as linoleum or concrete.
   2. You may also want to cover the surface (under the cardboard) with butcher paper or lots of newspaper to prevent stains.
4. Fill the medicine dropper with some simulated blood and hold the dropper completely vertically above the cardboard piece, as shown in Figure 4 below. Have a helper use the measuring tape to make sure the tip of the dropper is 30 cm (12 in) above the cardboard.

5. Drop a single drop of simulated blood onto the cardboard piece.
6. Repeat steps 4–5 nine more times so that you have dropped a total of 10 drops onto the cardboard piece. Then let the cardboard piece dry, being careful not to disturb the drops while they dry.
   1. If any of the drops landed on another drop or landed in a crease or fold on the cardboard, do not count these drops for your total of 10.
7. Repeat steps 3–6 with all of your other cardboard pieces, being sure to test each from the correct height.
   1. You and your helper will need to stand on chairs or stepstools to reach the highest heights. Be careful when doing this.
8. When all of the drops on the cardboard pieces have dried, measure the diameter of each drop — or spatter — in millimeters (mm) or inches (in) and record the measurements in your notebook in a data table like Table 1 below. Be sure to measure very carefully, because there may be very small, but measurable, differences between the drops. Tip: The drops may look glossy and wet even after they have dried. You may want to make an extra drop on one of the cardboard pieces that you can test (by touching it) to see when the drops have completely dried.

Drop height (cm) or (in)	Drop	Drop diameter (mm) or (in)	Average drop diameter (mm) or (in)
30	1
	2
	3
	…
	10
60	1
	2
	3
	…
	10
90	1
	2
	3
	…
	10
etc.	etc.

9. Calculate the average diameter of the drops for each height. Add your answers to your data table.
   1. For example, if the 10 drops you measured at a height of 90 cm (36 in) had diameters of 12.5 mm (0.49 in), 12.0 mm (0.47 in), 12.5 mm (0.49 in), 13 mm (0.51 in), 12.5 mm (0.49 in), 13 mm (0.51 in), 12.5 mm (0.49 in), 12.0 mm (0.47 in), 13.5 mm (0.53 in), and 12.0 mm (0.47 in), the average drop diameter from a height of 90 cm (36 in) would be 12.6 mm (since the sum of all 10 drops is 125.5, and this number divided by 10 rounds to 12.6 mm (0.50 in).
10. Make a graph of your results. On the x-axis, put the drop height (cm or in), and on the y-axis, put the average drop diameter (mm or in).
11. Look at your graph and try to draw some conclusions based on your results.
    1. How did the diameter of the spatter change as the simulated blood was dropped from different heights?
    2. How do you think your results could help a forensic scientist figure out what happened at a crime scene?

This activity is brought to you in partnership with Science Buddies. Find the original activity on the Science Buddies website.

Plastic pollution is a major issue worldwide, and plastic production has been increasing for decades. Mass production of plastic is not sustainable for the environment, and recycling plastic alone will not address the problem of plastic pollution. Plastic pollution has negative effects on the environment, impacting ecosystems and the organisms in them, including us. Although we do not currently know whether plastics alone are harmful to human health, emerging research suggests they may be associated with human immune disorders and developmental, reproductive and neurological issues. Better understanding the impacts on animal and human health is an active area of research.

Why is plastic pollution such a big problem? Some plastics take an extremely long time to break down, or degrade, and even this process itself can cause problems. Plastics can break down into microplastics, tiny pieces 5 millimeters (0.2 inch [in]) or smaller. Microplastics may not only contain harmful chemicals but can also bind to toxins. While much remains unknown about how microplastics may affect living organisms, ingesting them (and any bound toxins) may be harmful to our bodies and ecosystems.

Nearly half of plastic pollution can float, and it ends up in the oceans or washed up on beaches. Ocean microplastics are consumed by a range of marine organisms, including fish, marine mammals and seabirds. Microplastics may also accumulate in fish that we eat. The Great Pacific Garbage Patch is a gigantic collection of marine debris — plastic and other floating trash — in the central North Pacific Ocean, weighing about 100,000,000 kilograms (kg) (220,000,000 pounds [lbs]).

Efforts are underway to tackle this enormous challenge. By the end of 2024, scientists and others with the Ocean Cleanup project had removed about 500,000 kg (1,100,000 lbs) of trash from the Great Pacific Garbage Patch, but that was only half a percent of the total amount of garbage! While only about 8 percent of plastic in the Great Pacific Garbage Patch is microplastics, larger plastic pieces continually break down, creating more microplastics, and these pieces are much harder to clean up. Plastic trash and particles are now found in most marine and terrestrial habitats, including rivers, lakes, ponds, beaches, coral reefs and the deep sea.

What can we do about plastic pollution? In this science project, you will investigate how floating microplastics can be removed from contaminated water. To clean water at a wastewater treatment plant, flocculants are added. Flocculants clump together with particles floating or suspended in the water. These clumps, called flocs, can then sink and settle to the bottom of a water container, making it easier to remove both the flocculants and the particles. This process is called flocculation. (Sedimentation is another term used to describe how particles sink and settle at the bottom of a container or body of water.)

To help make sure that flocculants do not harm organisms living in or using the water, scientists are investigating using bioremediation instead of chemicals during flocculation. Using organisms (usually microscopic organisms, or microorganisms) to remove environmental pollutants is called bioremediation. Watch the video below to learn more about bioremediation.

In this project, you will investigate how baker’s yeast (Saccharomyces cerevisiae) can be used as a flocculant to sediment microplastics in contaminated water. For the microplastics, you will use plastic glitter.

Terms and concepts

• Microplastics
• Great Pacific Garbage Patch
• Wastewater treatment plant
• Flocculants
• Flocs
• Flocculation
• Sedimentation
• Microorganisms
• Bioremediation
• Yeast

Questions

• Why might floating microplastics be a problem in water systems such as rivers, lakes and oceans?
• How is flocculation used in a wastewater treatment plant?
• Do some research into flocculants used in wastewater treatment plants. How do flocculants usually work?
• How is bioremediation different from other methods used to remove pollutants from the environment?

Resources

• The Ocean Cleanup. (2026). Ocean Plastic Pollution Explained. Retrieved March 27, 2026.
• Environmental Protection Agency (EPA). (2026, January 12). Sustainable Management of Plastics. Retrieved March 27, 2026.
• Wikipedia. (2026, March 26). Bioremediation. Retrieved March 27, 2026.
• Wikipedia. (2025, July 6). Sedimentation (water treatment). Retrieved March 27, 2026. 

Materials and equipment

• Common lab supplies:
  • Economy pocket scale – 750 * 0.1 g or other digital scale with 0.1 g increments
  • 100 mL graduated cylinder or liquid measuring cup
• Glitter (36 grams)
  • Standard plastic glitter should be used. The glitter should be made of polyethylene terephthalate (PET), also called polyester. It should float when mixed with water.
• Jars with lids, 8-ounce size (4)
  • Canning jars work well for this.  
• Wax paper (1 sheet)
• Baker’s yeast (11 g)
• Timer, clock or stopwatch
• Helper for shaking the jars
• Optional: Camera
• Lab notebook

Experimental procedure

Prepare each jar

1. Add 3.0 grams (g) (0.1 ounce [oz]) of glitter to each jar.
   1. To weigh out the glitter, cut a small piece of wax paper — around 8 centimeters (cm) to 10 cm (3 to 4 in) on each side, place the wax paper on the scale, zero out the scale (so that it reads “0 g”), and then weigh out the glitter on the wax paper, as shown in Figure 2.
2. Add 0.5 g, 1.0 g or 2.0 g (0.02 oz, 0.04 oz or 0.08 oz) of yeast to each jar. Add no yeast to the fourth jar.
   1. Weigh out the yeast as you did for the glitter in step 1i.
   2. Label each jar with how much yeast is in the jar.
3. Add 200 mL (about 1 cup [C]) of water to each jar.
   1. Use the graduated cylinder to measure and pour the water.
4. Each jar should now be filled almost to the top, with some empty space between the top of the liquid and the jar’s lid, as shown in Figure 3.
5. Screw the lids onto each jar securely.

Shake the jars

1. Shake each jar at high speed for two minutes (min).
   1. Use a timer, stopwatch or clock to keep track of time.
   2. Have a helper shake two of the jars (one in each hand) so all jars are shaken similarly and start at the same time.
   3. Shaking vigorously will help mix the yeast and glitter.
2. Shake each jar at a lower speed for an additional five min.
   1. Repeat the shaking as you did in step 1, but at a lower speed.
   2. This will help ensure the yeast and glitter are thoroughly mixed.
3. Set all jars next to each other in a flat, out-of-the-way location (such as a table or counter) where they will not be moved or bumped for the next hour. Also, make sure there is enough light to make observations.

Observe the jars

1. Leave the jars undisturbed for 60 min, but make and record observations during this time.
   1. In your lab notebook, create a data table similar to Table 1.
   2. Record any observations at the indicated times (0, 15, 30, 45 and 60 min).
      1. How does the glitter look in each jar?
         1. At the 0 min time point, the glitter in the jar with no yeast (i.e., your control) should be floating at the top.
      2. Can you tell where the yeast is in the jars?
      3. Do the jars with the yeast look different in some way? How do they look similar?
   3. After 60 min, carefully remove the lid from each jar, moving the jar as little as possible, and perform final observations. Record these observations in your data table, too.
      1. Is there glitter floating on the top of the water? If yes, how is the amount of floating glitter in each jar similar or different?
      2. Where is the glitter in each jar?
      3. Where is the yeast in the jars with yeast?

	No Yeast	0.5 g (0.02 oz) Yeast	1 g (0.04 oz) Yeast	2 g (0.08 oz) Yeast
0 min
15 min
30 min
45 min
60 min

Measure the suspended or floating glitter

1. Set up a strainer with a coffee filter and place the strainer over a large container to collect the liquid that flows through. Your setup should look similar to Figure 4. You will be using this setup to collect the glitter floating and suspended in each jar.
2. Slowly pour the jar with no yeast through the coffee filter but stop pouring before any glitter that has settled on the bottom is disturbed. You will stop pouring to ensure you measure only the glitter that is floating or suspended in each jar, not the glitter that has settled to the bottom.
3. After the liquid has flowed through:
   1. Carefully lift off the coffee filter and set it aside to dry.
   2. Use a marker or pen to label the edge of the coffee filter with the sample that you poured through it.
4. Repeat steps 2 to 3 with a new coffee filter in the strainer, and this time slowly pour the jar with 2.0 g (0.08 oz) yeast through the coffee filter. As before, stop pouring before any layer of settled glitter or yeast is disturbed. Again, you want to ensure you measure only the glitter floating or suspended in each jar, not the settled glitter at the bottom.
5. Repeat step 4 with the remaining two jars.
6. While each coffee filter is drying, make a data table like Table 2 in your lab notebook.
7. After each coffee filter has completely dried, which may take at least an hour, weigh the glitter on it and record the weight in Table 2.
   1. Zero out the scale (so that it reads “0 g”) using a fresh coffee filter.
   2. Then weigh each coffee filter with the glitter on it from the jar.
      1. Tip: Be sure each coffee filter is completely dry, or your weight measurements will be inaccurate.

	No Yeast	0.5 g (0.02 oz) Yeast	1 g (0.04 oz) Yeast	2 g (0.08 oz) Yeast
Weight of suspended or floating glitter (g)

8. Repeat the procedure two more times. Scientists always repeat their experiments to make sure their findings are true and reproducible.
9. When you are done with your experiment, do not pour any glitter down the sink, but instead dispose of it by sealing it in a bag and placing it in the trash.
10. What do your results tell you about which conditions lead to glitter sinking and settling to the bottom of each jar?
    1. Which jar had the most glitter still floating or suspended after 60 min?
    2. Which jar (or jars) had the most glitter settle to the bottom?
    3. How much yeast is needed to cause glitter to settle to the bottom?
    4. How do the jars with yeast compare to the control jar (with no yeast)?
    5. What do your results tell you about potential bioremediation strategies for microplastics?
    6. Can you think of ways to improve upon the bioremediation strategy that was most successful in your science project? You can also check out the Variations section, below, for additional ideas.

Variations

• In this project, you used baker’s yeast in your bioremediation experiments. What other organisms could you use to test their ability to remove water pollutants?
• This science project involved adding baker’s yeast to clean up contaminated water. While such an approach may work for cleaning contaminated wastewater, adding baker’s yeast may not be as feasible for cleaning contaminated waters in the ocean and other natural water systems. What other methods could be used to safely and efficiently remove microplastics from natural water systems? 
• Biofilms may trap floating microplastics. Do some research into biofilms. How could you safely test the ability of biofilms to remove floating microplastics from contaminated water?
• Here, you used glitter as an example of microplastics. Explore what other types of microplastics pollute water systems. How could you test ways to remove other types of microplastics from contaminated water?
• Biodegradable hydrogels are being explored for their potential to safely remove pollutants from water. How could you test the ability of hydrogels to remove pollutants from water? 
• Do some research into other types of pollutants that contaminate various water systems, such as rivers, lakes and oceans. For example, dyes and high levels of sugars can pollute some water systems. Pick a different type of pollutant and research how it can be removed from water. How could you test how effective different approaches are in removing your chosen pollutant from contaminated water?
• Some microplastics can bind to toxins, making their ingestion more hazardous. Can you design a way to model this, for example, by exposing different plastics to different dyes and measuring how well each plastic changes color when stained with each dye?

This activity is brought to you in partnership with Science Buddies. Find the original activity on the Science Buddies website.

Computer-generated images have been around for decades. People use computers to make digital art and animations for movies, TV shows and video games. However, just like making a physical painting with a paintbrush, these images take a lot of time and human effort to produce.

The rise of artificial intelligence has drastically reduced the amount of time and effort it takes to create computer-generated images. New programs and websites can generate images using a text prompt from the user, such as “a picture of a tiger walking through a grassy field.” These programs can automatically generate artwork and photo-realistic images that can be difficult to tell apart from “real” photos and artwork. Can you tell which picture at the top of this story is real and which is AI-generated?

While AI-generated images might seem fun or harmless, they can also cause problems. People can use them to create deepfakes, or fake images of things that did not really happen. Some people might see the picture and believe that it is real. While fake news and fake images have been around for a long time, AI tools can make it easier and faster to produce this misleading content.

Can people tell the difference between real pictures and AI-generated pictures? How hard is it to spot “fake” pictures? In this science project you will find out!

Terms and concepts

• Computer-generated image
• Artificial intelligence
• Deepfake

Questions

• What are some uses for AI-generated images?
• What are some potential problems caused by AI-generated images?

Resources

• Axios (2023, July 31). How to spot deepfakes created by AI image generators. Retrieved September 14, 2023.
• Bond, S. (2023, June 13). AI-generated images are everywhere. Here’s how to spot them. NPR. Retrieved September 14, 2023.

Materials and equipment

• Internet access
• Digital camera or smartphone
• Optional: printer
• Volunteers
• Lab notebook

Experimental procedure

1. Decide on a topic or theme for your pictures. For example, you could use pictures of animals, flowers, scenery, vehicles or people.
2. Take at least 10 real pictures of the object/topic you decided on or find pictures online.
   1. Make sure you label or organize the images so you do not lose track of them later. (As an example, you could put all the real pictures in a folder on your computer.)
   2. If you are finding the pictures online, make sure they are from a legitimate source and you know they are real pictures. (See references in the Bibliography for tips.)
3. Find or make at least 10 AI-generated images of the same object/topic.
   1. You can search online for an “AI image generator” and you will find many options available. Some services might be built into major search engines. Others might have their own websites. Also note that some services might be free, or allow you to generate a limited number of images for free. But others might require a paid subscription.
   2. Follow the instructions for the website or program you decide to use to enter a prompt and generate an image. Since you will be comparing them to real images, make sure you generate “realistic” photos and not images that look like paintings or drawings.
   3. Save the images. Again, make sure you keep track of which images are real and which are AI-generated.
4. Prepare all the images for viewing by your volunteers. For example, you can label them 1 through 20 and put them in a random order in a different folder on your computer. Or you could print them. Make sure you keep track of which images are real and which are AI-generated. But this information should not be visible to your volunteers.
5. Prepare a data table like Table 1. In the second column, write whether each image is real or AI-generated.

Image number	Real or AI generated	Volunteer  1	Volunteer 2	Volunteer 3	Volunteer “real” responses	Volunteer “AI” responses	% of volunteers correct

6. One at a time, show each picture to a volunteer. Ask them whether they think the picture is real or AI-generated. Record their response in your data table.
7. Repeat the process for each volunteer.
8. For each image, add up the number of volunteers who said the image was real. Enter this value in your data table.
9. For each image, add up the number of volunteers who said the image was AI-generated. Enter this response in your data table.
10. Calculate the percentage of volunteers who correctly identified whether each individual image was real or AI-generated. Enter the percentage in your data table.
11. Create another data table like Table 2.

		Volunteer responses
		Real	AI-generated
Actual image	Real
	AI-generated

12. Analyze your data.
    • Overall, how good were your volunteers at correctly identifying real images as real?
    • Overall, how good were your volunteers at correctly identifying AI-generated images as AI-generated?
    • Are there large differences in your results between individual pictures? Were some pictures harder for your volunteers to correctly identify than others? Looking at the pictures, why do you think this occurred?

Variations

• Repeat the experiment with artwork instead of pictures. Can your volunteers tell the difference between real artwork and AI-generated art?
• Do the experiment with two groups of volunteers: a control group and a group that you have trained to spot AI-generated images. (See some of the references in the Bibliography.) Can people with training do a better job correctly identifying the images?
• Try the experiment with different categories of images/objects. Are some things easier for people to recognize than others? For example, what about pictures of inanimate objects vs. pictures of living things? What about pictures of “regular” people vs. famous people like politicians or actors?
• Compare different AI image generation websites or services. Are some better than others at producing convincing images?
• Do an experiment to find out if people can recognize AI-generated text instead of images.
• Can you produce fake news articles that include both images and text about real people or events? Run the experiment with both real and fake news articles. Can people tell which is which?

This activity is brought to you in partnership with Science Buddies. Find the original activity on the Science Buddies website.