Gummy bear osmosis
01 // Question
How does the type of liquid a gummy bear soaks in change its mass overnight?
A gummy bear is a gelatin gel, not a cell membrane; use it as a limited model for visible water uptake.
02 // Variables
Independent
Liquid the gummy bear soaks in- Distilled water
- Salt water (about 10%)
- Vinegar (exploratory gel comparison)
Dependent
Change in gummy bear mass and longest length- Mass before and after, to 0.01 g
- Percent mass change
- Longest length before and after, in cm
03 // Hypothesis
IF a gummy bear soaks in plain water instead of salt water, THEN it will gain more mass than the bear in salt water, BECAUSE water can enter and become held in the gelatin network, while solution concentration and candy ingredients affect the measured change.
04 // Procedure
1. Measure dry bears
For each same-brand bear, record starting mass to 0.01 g and its longest length in centimeters before soaking.
2. Pour the liquids
Add 100 mL to each labeled cup. Compare water with salt water for the concentration question; treat vinegar as an exploratory comparison because acidity can alter gelatin.
3. Soak overnight
Drop one bear into each cup and let them sit undisturbed for 24 hours.
4. Blot and measure again
Lift each bear out with a spoon, blot gently the same way, record final mass, then measure its longest length without squeezing.
5. Calculate the change
Find the mass change and percent change for each bear.
Materials // Prepare the bench
- Same-brand gummy bears
- distilled water
- salt
- vinegar
- labeled cups
- balance
- graduated cylinder
- spoon
- paper towels
05 // Data table
| Liquid | Start mass (g) | After soak (g) | Change (g) | % change | Length before → after (cm) |
|---|---|---|---|---|---|
| Distilled water | ____ | ____ | ____ | ____ | ____ → ____ |
| Salt water | ____ | ____ | ____ | ____ | ____ → ____ |
| Vinegar (exploratory) | ____ | ____ | ____ | ____ | ____ → ____ |
Formula % change = (mass after − start mass) ÷ start mass × 100
06 // What to expect
A typical result is that a bear gains mass in plain water. Salt water may reduce that gain or produce a loss, depending on its concentration and the candy. Treat these as predictions to test: gummy candy is a gelatin gel, not a selectively permeable cell membrane, so mass and size changes do not isolate osmosis by themselves.
Vinegar may soften or partly dissolve the gelatin, so its result can reflect changes to the gel as well as water uptake. Compare vinegar as an exploratory treatment and do not use it alone to infer osmosis.
07 // Lab notes
- Use bears from the same bag and pick a consistent color, since bag position and size can vary the starting mass. When supplies allow, test at least three bears per liquid and compare individual results with the mean.
- Don't leave bears soaking longer than 24 hours — they start to dissolve and fall apart, which throws off the mass reading.
- Blot each bear the same way before weighing, so leftover surface liquid does not add extra mass to the reading.
08 // Remember
Gummy candy is a gel, not a cell. Measure how its mass and shape respond to each liquid.
09 // Keep the candy comparison controlled
Choose bears from the same package and sort them by color or starting mass so the comparison does not accidentally become a comparison of different candy recipes. Record each dry bear's mass before soaking. Use the same liquid volume, cup shape, temperature, and soak time for every sample. For a 10% salt solution by mass per volume, dissolve 10 g of salt and add water until the final solution volume is 100 mL; do not add the salt to 100 mL of water. A gummy bear can swell enough to press against the cup, so leave room above the liquid and identify each cup before the bears go in.
The liquid is the independent variable and the bear's mass or dimensions are dependent measurements. When supplies allow, test at least three bears in each treatment and compare every result with the mean instead of treating one unusually shaped candy as decisive. Use a spoon to lift each bear and blot it with the same light touch. Pressing hard can squeeze liquid out and make the final mass depend on who handled the sample.
10 // Interpret a model without overclaiming
Calculate mass change and percent mass change for every bear. A larger percentage makes it easier to compare candies that began at different sizes. The outside solution's dissolved material affects water movement into or out of the gelatin-and-sugar network, but candy is not a living cell. Its ingredients, gel structure, and the liquid itself all affect the result. Use the experiment as a model for movement and concentration, not as proof that a gummy bear has a cell membrane.
Compare the shape and firmness as well as mass. A bear can gain mass while becoming soft, because liquid entering the gel changes its structure. Salt water and vinegar are not identical treatments: salt changes dissolved-particle concentration, while vinegar also changes acidity. If the class wants to test concentration specifically, use several measured salt concentrations and keep pH and other conditions as similar as practical.
11 // Improve reliability and ask a sharper question
Gummy bears vary from piece to piece, so replicate each treatment. If one bear breaks, record the damage and exclude it from a size measurement that can no longer be made consistently. Measure all bears after the same soaking interval, and photograph them beside a ruler before and after if width and height are part of the question. Never taste experimental candy; it has been handled with lab liquids and equipment.
Students can graph percent mass change by liquid, with each treatment on the horizontal axis and average percent change on the vertical axis. Add the individual measurements as dots so the spread is visible. A next investigation might test soak duration, sugar concentration, or temperature, but change only one of those factors at a time. State the limit in the conclusion: the result describes these candies, liquids, and conditions, not all cells or all foods.
12 // Track shape as well as mass
Mass change is a useful measurement, but dimensions and firmness can reveal how a gummy bear's gel structure responds to liquid. Measure length and width at the same locations with light pressure; squeezing the candy can distort the reading and force liquid out. Photograph each sample beside a ruler using the same camera distance if visual comparison is part of the report.
Candy ingredients and colorings vary between brands, so identify the package and avoid generalizing to all gels or living cells. Keep the soak time and blotting routine consistent, then compare individual bears as well as group averages. Experimental candy is not food after contact with lab containers and liquids.
13 // Questions people ask
Why does a gummy bear often gain mass in water?
Water can enter and become held within the gelatin network, so the bear often gains mass and expands. Gummy candy is not a selectively permeable cell membrane, so this classroom model does not isolate osmosis as neatly as a living-cell membrane model.
Will salt water always make a gummy bear shrink?
No. The result depends on the salt concentration, candy recipe, soak time and measurement method. Salt water may reduce mass gain or cause mass loss; measure your sample instead of treating shrinkage as guaranteed.
What is the independent variable in the gummy bear soaking lab?
The soaking liquid is the independent variable; mass change and size observations are dependent measurements. Water and salt water make a clearer concentration comparison, while vinegar is an exploratory treatment because acidity can also change gelatin.
14 // Keep going
Can you explain the investigation?
Gummy bear osmosis · Student Data Sheet
Question: How does the type of liquid a gummy bear soaks in change its mass overnight?
Hypothesis: If a gummy bear soaks in plain water instead of salt water, then it will gain more mass than the bear in salt water, because water can enter and become held in the gelatin network, while solution concentration and candy ingredients affect the measured change.
Materials
- Same-brand gummy bears
- distilled water
- salt
- vinegar
- labeled cups
- balance
- graduated cylinder
- spoon
- paper towels
Safety before starting
- Check ingredient labels for allergies and keep small candies away from young children. Never eat bears after soaking or handling; samples and liquids are not food.
- Keep labeled cups on a stable tray, avoid splashes near eyes and mouths, wash hands after handling, and follow teacher directions for salt-solution and vinegar disposal.
Lab notes
- Use bears from the same bag and pick a consistent color, since bag position and size can vary the starting mass. When supplies allow, test at least three bears per liquid and compare individual results with the mean.
- Don't leave bears soaking longer than 24 hours — they start to dissolve and fall apart, which throws off the mass reading.
- Blot each bear the same way before weighing, so leftover surface liquid does not add extra mass to the reading.
Variables
Independent: Liquid the gummy bear soaks in · Dependent: Change in gummy bear mass and longest length
Keep constant: same brand and color of bear · 100 mL of liquid per cup · room temperature · same soak time · same size cup
Procedure
- Measure dry bears: For each same-brand bear, record starting mass to 0.01 g and its longest length in centimeters before soaking.
- Pour the liquids: Add 100 mL to each labeled cup. Compare water with salt water for the concentration question; treat vinegar as an exploratory comparison because acidity can alter gelatin.
- Soak overnight: Drop one bear into each cup and let them sit undisturbed for 24 hours.
- Blot and measure again: Lift each bear out with a spoon, blot gently the same way, record final mass, then measure its longest length without squeezing.
- Calculate the change: Find the mass change and percent change for each bear.
Record your observations
| Liquid | Start mass (g) | After soak (g) | Change (g) | % change | Length before → after (cm) |
|---|---|---|---|---|---|
Formula: % change = (mass after − start mass) ÷ start mass × 100
Answer key and expected pattern
A typical result is that a bear gains mass in plain water. Salt water may reduce that gain or produce a loss, depending on its concentration and the candy. Treat these as predictions to test: gummy candy is a gelatin gel, not a selectively permeable cell membrane, so mass and size changes do not isolate osmosis by themselves.
Vinegar may soften or partly dissolve the gelatin, so its result can reflect changes to the gel as well as water uptake. Compare vinegar as an exploratory treatment and do not use it alone to infer osmosis.
Remember: Gummy candy is a gel, not a cell. Measure how its mass and shape respond to each liquid.