Materials
Two resealable plastic bags Hot water
Ice water Red food color
Instructions
1. Pour 1 cup (250 ml) of ice water into a resealable plastic bag.
2. Drop in 3 drops of red dye, zip it shut and try not to jiggle the bag.
3. Watch what happens to the red dye. Check the time to see how long it takes the dye to turn all the water red.
4. The children are observing the process called "diffusion" which will cause the two different kinds of molecules to mix. The red dye molecules will spread from where there are more of one kind to where there are fewer of the same kind.
5. Next, pour 1 cup (250 ml) of hot tap water into another bag. Add 3 drops of red dye and seal. Observe how long it takes the dye to turn the water red. Are there differences depending on water temperature?
