Why do some things sink and some things float? Density is why!
Materials: bowl or small pail, water, a coin, clay, different objects that will sink or float, paper towels, notebook or paper, pen or pencil
Grades: 3rd and up
Time: 30 minutes
Density measures how heavy an object is compared to its size. If an object’s density is greater than water’s density, it will sink when placed in water. If it is less dense than water, the object will float.
- Gather and set up your materials. First, get a large bowl and fill it with water. Then, find a coin and other household objects that can go in water, such as a paper clip, cork, ping-pong ball, or button.
- On your paper, make a list of each item you have. Next to your item, draw a line to make a new column. Next to each item, predict whether it will sink or float when you put the object in the bowl of water. Write your predictions in the new column.
- Now it’s time to test your predictions! Pick one object to place in the water and observe what happens. Check your observation against your prediction. When your prediction was correct, place a checkmark next to the item. Repeat these steps for each object.
- Answer the following questions:
- Were your predictions correct?
- What are some of the qualities of objects that sink?
- What are the qualities of objects that float?
- How can you make a penny float? (Hint: you might have to combine objects together)