What You Need:
- Variety of objects from around the house (examples: empty egg carton, full juice box, apple, banana, box of raisins, toy block, magazine, small wicker basket, picture frame, toothbrush, coffee mug)
- Kitchen scale (for small items)
- Bathroom scale (for large items)
- Lined paper
What You Do:
- Set it up. Start by telling your child that you will be doing some science together. You'll begin by looking at some regular things and making guesses (hypotheses) about which one is heavier. Check your young scientist's knowledge: how will we know which items are heavier than others? (Expect the answer, “I'll hold them,” and don't be surprised if your kid adds, “Duh.”) Do continue, however: remind your child that to be absolutely accurate, he'll also need to weigh the items. Depending on your scale, you may even want to introduce the concept of weighing in either pounds and ounces, or in grams. Now help your child make an “observation” chart on his lined paper. Write “Heavy or Light” on the top, and then fold the paper in half lengthwise. He'll use the chart to write the names of objects, or a picture of them if he prefers, and to record which is heavy or light.
- Gather the items. Assemble all of the chosen objects on a table or countertop. Ask your child to name or point to two objects. Move those objects so they are next to each other and separate from the other objects. It's important for you to do this step, as your child will get a chance to handle the objects later in the activity.
- Make predictions. Ask your child just to look at both objects she selected. Look at their height, length, shape, and any other distinctive features. Ask her to tell you, just from looking at them, which object she thinks is heavier.
- Evaluate. Once your child has guessed, ask her to pick up the objects. Ideally one in each hand works the best, but if an object is too heavy, it may be picked up individually. Ask your child if she wants to change her guess or keep it the same.
- Weigh in. Using a kitchen or bathroom scale (whichever is more appropriate) weigh the two objects. Was your child right? If not, can she figure out why their guess was wrong? Talk about how the scale measures the mass (weight) of an object, but some things may have lots of volume (size) with very little mass. Write the weight of each object below its name or picture on the observation chart.
- Repeat. Place those objects aside and ask your child to pick two more to compare.
Repeat these steps as long as your child is interested in the activity…and don't hesitate to pull it out as you explore new things, whether it's seashells from the beach or pinecones from the forest. The world is crammed with exciting reminders that when it comes to volume and mass, what you see is not always what you get…and that's a very cool thing indeed.