Have you ever forgotten to throw out some old fruit, only to have it go bad? This probably leaves your child wondering why food looks and smells that way when it spoils. This experiment will let your child observe as food decomposes by taking photos to keep note of what's going on. On top of that, he will be able to practice some basic scientific principles by making observations and predictions.
Bits of old food (fruits and bread work best, but stay clear of meat and milk products)
Notebook and pen
What You Do:
Begin by asking your child to tell you about any time that he's seen rotten or spoiled food, and ask what he thinks happened to the food.
Then ask if he knows what the word decompose means. Explain that decomposing is the natural process of food breaking down after it gets too old to eat. (Stress the idea that decomposing food is not safe to eat.)
When you're finished discussing this, get your three jars and find a warm place in the house. Be sure that wherever you place the jars, they remain out of reach from babies and pets!
Then, get your cotton balls and bits of food. Have your child put some cotton balls in one jar and some food bits in another. Put the jar on tightly so that the smell of the rotten food won't escape.
Ask him to predict what will happen to the cotton balls and what will happen to the bits of food, and write it down in the notebook.
Every other day, have your child take a picture of what's inside the jars to record the progression. Also, have him record his observations by date in a notebook.
At the end of two weeks, look carefully at the food in the jar. If the food isn't too smelly (and you think you have the stomach to handle it) you can remove it and have your child look at it with a magnifying glass. Then discard the food safely, making sure that no one eats it.
Then, develop the pictures or if you have a digital camera, print the pictures.
Once the pictures are developed, glue them in sequence onto the poster board with the date clearly written underneath each photo.
Next time you find rotten food in your fridge, talk with your child about what he learned from the decomposing experiment!