Add a spoonful of baking powder and stir. (Watch out, it will fizz!)
Note the color change. Discuss: What could have caused this?
Now, add a little bit of citric acid or lemon or lime juice to the cup (Careful, it will fizz again!)
The juice should start changing color (If it is not fully changed, add a little more acid)
Discuss: Why do you think the color changed again?
The Science Behind It
Cranberries contain chemicals called anthocyanins, which change color depending on how acidic their surroundings are. This means, they are natural pH indicators! Since cranberries are naturally acidic, they normally look red, but we can neutralize the acid and watch the colors change.
Cranberry Juice PH Video
Tips
If you are curious and want to expand on this experiment, try it out multiple times with different acids and bases! See how many color variations you could get. If project participants are older, consider writing hypothesis’ before beginning the experiment.