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starScience Activities

Apple Dunk

Have you ever wondered why a sliced apple turns brown when you leave it exposed to the open air? Now you can find out the answer—and teach it to your kids—with this fun and simple activity, which really lets your kids see chemistry in action. Your children will come to understand that it is exposure to oxygen that makes the sliced apple turn brown. By coating the sliced apple in another substance, however, you can keep it safe from the oxygen, and keep it whiter longer!

Activity Instructions

Take an apple and slice it into at least three pieces. Take one slice and put it in a bowl of shallow water -- just enough water to completely cover the slice of apple.

Take a second slice and coat it with lemon juice. Leave the third slice out in the open, unaltered.

While the kids are waiting to see what happens, have them complete the Science Experiment Journal to document the project and answer questions about what they think will happen.

Instruct your child to carefully examine each of the three apples, and talk with them about what they see.

  1. The apple that is submerged in water will not turn brown immediately; the water covers it and keeps it safe from the effects of the oxygen in the air.
  2. The lemon juice, meanwhile, binds with the oxygen, which keeps that oxygen away from the apple. The lemon-juiced slice should stay brown even longer than the one underwater.
  3. The third slice of apple, meanwhile, is the one most exposed to the air, and therefore it will turn brown much quicker than the first two.


  • An Apple (any kind of apple will do.)
  • Half of a Lemon (or just a bottle of lemon juice)
  • A Shallow Bowl
  • A Knife (for slicing the apple)
  • Tap Water
  • Science Experiment Journal


When an apple is sliced and exposed to the open air, chemicals within it combine with oxygen and make the apple turn brown. This is an excellent way to show your children some basic science in action, and to talk with them about how different substances—like oxygen and the chemicals in an apple, or oxygen and lemon juice—combine in unique and fun ways.