Skittles diffusion experiment
01 // Question
How does water temperature affect the time a Skittles color front takes to reach the center of a plate?
This measures visible transport from a dissolving candy coating; diffusion and water currents can both contribute.
02 // Variables
Independent
Water temperature- Cold water · target 10–15°C
- Room-temperature water · record the actual value
- Comfortably warm water · target 35–40°C
Dependent
Seconds from the end of the matched pour until the first color front reaches the plate center- Record “not reached” at the five-minute observation limit
03 // Hypothesis
IF a matched ring is tested with comfortably warm rather than colder water, THEN the first color front may reach the center sooner in these trials, BECAUSE higher temperature can speed up coating dissolution and molecular spreading, although water currents can also move the color.
04 // Procedure
1. Arrange the ring
Place twelve Skittles in the same color order and even spacing around the inside edge of a level white plate.
2. Measure the water
Use 100 mL for each trial. Record its temperature just before pouring: target 10–15°C cold, actual room temperature, and 35–40°C comfortably warm water.
3. Pour carefully
An adult prepares and pours the warm water. Use the same gentle five-second center pour without moving candies or plate.
4. Time the spread
Use the same gentle five-second pour for each 100 mL sample. Start the timer when the pour ends; stop when the first color front reaches the plate center.
5. Record and repeat
Record the measured water temperature and time, then fully dry the same plate and use fresh candies for the next trial. Run two trials per condition in the short lesson; add a third if time and supplies allow.
Materials // Prepare the bench
- 12 Skittles in a repeatable color order
- level white plate
- 100 mL cold, room-temperature, and comfortably warm water
- thermometer
- measuring cup
- timer
- paper towels
05 // Data table
| Water temperature (°C) | Trial 1 (s) | Trial 2 (s) | First front reached center? |
|---|---|---|---|
| Cold (target 10–15) | ____ | ____ | ____ |
| Room (record actual) | ____ | ____ | ____ |
| Comfortably warm (target 35–40) | ____ | ____ | ____ |
Read the pattern without overclaiming
| What you observe | Possible influence | What you can conclude |
|---|---|---|
| A front reaches the center sooner | Coating dissolving, diffusion, or water currents | This setup showed faster visible transport; it did not isolate diffusion alone. |
| Color bands stay distinct briefly | Shallow, mostly still water and separate starting zones | The bands have not mixed much yet; diffusion continues. |
| A streak bends to one side | Plate tilt or uneven pouring | Record the irregularity and repeat on a level, dry plate. |
Formula Compare each pair of times; for a descriptive mean, (trial 1 + trial 2) ÷ 2. Keep both readings visible. A third trial can help assess repeatability when time permits.
06 // What to expect
Warm water often dissolves the candy coating and spreads its dye more quickly, but the visible pattern also depends on water currents, plate tilt and how the water is poured. The activity can introduce dissolving and diffusion; it does not isolate diffusion as the only process.
Distinct color fronts may remain visible during a short, still-water demonstration because the liquid has not mixed completely. The bands do not stay separate because every dye diffuses at exactly the same rate; gentle convection or moving the plate can blur them much sooner.
07 // Lab notes
- Have an adult prepare comfortably warm (35–40°C), not hot, water. Use 10–15°C cold water and record the actual room-water temperature; keep every pour gentle and the same length.
- Use the same gentle five-second pour for each 100 mL sample. Start timing when the pour ends and stop when the first visible color front reaches the plate center; keep this rule for every run.
- Use a completely dry, clean plate for each trial so leftover color doesn't skew the timing.
- Check candy allergies and school food-handling rules. Test candy is not food to eat; wipe colored spills promptly because the sugar solution can make a surface slippery.
08 // Remember
Warm water can speed dissolving and spreading. Keep the plate level and still so currents do not dominate the color pattern.
09 // Build a repeatable diffusion setup
For this comparison, arrange 12 candies in the same color order and evenly spaced ring on a clean, dry, level white plate. Measure 100 mL for every run and record its starting temperature: target 10–15°C for cold water, record the actual room-water temperature, and use 35–40°C for comfortably warm water. An adult prepares and pours the warm sample. Use the same gentle five-second pour at the plate center each time; start the timer when the pour ends and stop it when the first visible color front reaches the center. If it has not arrived after five minutes, record 'not reached' and the elapsed limit instead of making up a time.
Run two trials at each temperature for the short classroom version, using fresh candies and a completely dry plate every time; add a third repeat if time and supplies allow. Keep the plate still and level. A tilt or uneven pour can send colored water to one side, so record an imperfect run and its likely cause rather than quietly removing it. This visible endpoint combines candy-coating dissolution and movement through water; diffusion and currents can both contribute.
10 // Choose a measurable question
The main question changes only water temperature and measures seconds from the end of the same five-second pour until the first visible front reaches the plate center. Keep candy count/order/spacing, water volume, plate, pour location and duration, and timing rule constant. A different extension could instead compare spacing or water volume, but change one factor at a time and choose its measurement endpoint before collecting data.
Record both trial times and the actual starting temperature for each condition. Compare the two-run mean while keeping both readings visible; the mean describes these trials and does not erase variation. Warmer water can speed coating dissolution and molecular spreading, but pouring currents and other water movement also affect the observed front. Do not eat candies after they have been handled as lab materials.
11 // Interpret patterns and limitations
Symmetrical bands suggest that the candies were spaced evenly and water reached them at similar times. A streak that runs in one direction can point to a tilted plate, uneven pour, or a temperature difference in the water. Record these as possible sources of variation rather than discarding an inconvenient trial without explanation. A dye pattern is visible evidence of mixing and transport, but the colored bands do not show every molecular path.
For a deeper test, use a measured dye solution instead of candy and track the color boundary with a grid. That separates candy coating from diffusion and makes the measurement more controlled. Another extension can compare still water with gently stirred water, but stirring introduces an additional motion mechanism called convection. Explain which process the setup actually tested, and avoid labeling all visible spreading as diffusion if bulk water was moving.
12 // Control the conditions around the candy
The colored coating dissolves into water and moves outward, creating visible color fronts. For the core temperature test, use twelve candies in one spacing pattern, 100 mL of measured water, a level plate, and the same gentle five-second center pour. Start timing when the pour ends and stop at the first visible front at the center. Use fresh candies and a clean, dry plate for each repeat; record tilt or uneven-pour problems instead of silently dropping a result.
A separate extension can measure distance at a fixed interval, but it needs a consistent grid and timing point. Do not mix that outcome with the core center-arrival-time comparison. Test candy is not food, and wipe spills promptly because colored sugar solution can make a slippery surface.
13 // Questions people ask
Why does the color often spread faster in warm water?
Higher temperature can speed up the dissolving of the candy coating and molecular spreading of the dye. However, pouring currents, plate tilt, and water movement also affect the pattern, so this setup does not measure diffusion alone.
Why can the Skittles colors stay in separate bands for a while?
The water is mostly still, so the colored fronts can reach one another before much bulk mixing occurs. The bands are temporary: moving or tilting the plate creates currents that mix the colors, and molecular diffusion continues over time.
What is being measured in the Skittles color-spreading experiment?
This version measures elapsed seconds from the end of the same five-second pour until the first visible color front reaches the plate center. That visible time combines coating dissolution and movement through water; it is not a direct measurement of diffusion alone.
14 // Keep going
Can you explain the investigation?
Skittles diffusion experiment · Student Data Sheet
Question: How does water temperature affect the time a Skittles color front takes to reach the center of a plate?
Hypothesis: If a matched ring is tested with comfortably warm rather than colder water, then the first color front may reach the center sooner in these trials, because higher temperature can speed up coating dissolution and molecular spreading, although water currents can also move the color.
Materials
- 12 Skittles in a repeatable color order
- level white plate
- 100 mL cold, room-temperature, and comfortably warm water
- thermometer
- measuring cup
- timer
- paper towels
Safety before starting
- Do not eat candies after they have been placed on the test plate or touched by lab materials. Check for food allergies and keep small candies away from young children.
- An adult prepares and pours comfortably warm water at 35–40°C; do not use hot or boiling water. Food coloring can stain. Keep the plate on a stable surface, avoid splashing, wipe spills promptly and wash hands after the activity.
Lab notes
- Have an adult prepare comfortably warm (35–40°C), not hot, water. Use 10–15°C cold water and record the actual room-water temperature; keep every pour gentle and the same length.
- Use the same gentle five-second pour for each 100 mL sample. Start timing when the pour ends and stop when the first visible color front reaches the plate center; keep this rule for every run.
- Use a completely dry, clean plate for each trial so leftover color doesn't skew the timing.
- Check candy allergies and school food-handling rules. Test candy is not food to eat; wipe colored spills promptly because the sugar solution can make a surface slippery.
Variables
Independent: Water temperature · Dependent: Seconds from the end of the matched pour until the first color front reaches the plate center
Keep constant: 12 candies · same color order and spacing · 100 mL water per trial · same level plate · same pour time and point · measured starting temperature
Procedure
- Arrange the ring: Place twelve Skittles in the same color order and even spacing around the inside edge of a level white plate.
- Measure the water: Use 100 mL for each trial. Record its temperature just before pouring: target 10–15°C cold, actual room temperature, and 35–40°C comfortably warm water.
- Pour carefully: An adult prepares and pours the warm water. Use the same gentle five-second center pour without moving candies or plate.
- Time the spread: Use the same gentle five-second pour for each 100 mL sample. Start the timer when the pour ends; stop when the first color front reaches the plate center.
- Record and repeat: Record the measured water temperature and time, then fully dry the same plate and use fresh candies for the next trial. Run two trials per condition in the short lesson; add a third if time and supplies allow.
Record your observations
| Water temperature (°C) | Trial 1 (s) | Trial 2 (s) | First front reached center? |
|---|---|---|---|
Read the pattern without overclaiming
| What you observe | Possible influence | What you can conclude |
|---|---|---|
Formula: Compare each pair of times; for a descriptive mean, (trial 1 + trial 2) ÷ 2. Keep both readings visible. A third trial can help assess repeatability when time permits.
Answer key and expected pattern
Warm water often dissolves the candy coating and spreads its dye more quickly, but the visible pattern also depends on water currents, plate tilt and how the water is poured. The activity can introduce dissolving and diffusion; it does not isolate diffusion as the only process.
Distinct color fronts may remain visible during a short, still-water demonstration because the liquid has not mixed completely. The bands do not stay separate because every dye diffuses at exactly the same rate; gentle convection or moving the plate can blur them much sooner.
Remember: Warm water can speed dissolving and spreading. Keep the plate level and still so currents do not dominate the color pattern.