Did you know?
The idea of this activity is to develop a sense of unit to make plausible estimates. In other words, if you know how many fit into your hand then you have a unit to make a good guess on how many fit into a larger container. This is called “unitizing” and it is how scientists figure out how many small things (bugs, germs) are in a large area, or how many people are in a large crowd. It is impossible to count these items individually, so they use a known amount within a smaller area to estimate how many are in the larger area.
What you need
- Pennies (at least 500)
- Different sized clear containers
- Pencil and paper
- Penny Fact Questions (optional)
What to do
- Make a guess as to how many pennies you can grab with one hand out of a large pile of pennies.
- Now grab one handful of pennies.
- Count out how many pennies you grabbed.
- Choose a container and estimate how many handfuls it will take to fill it.
- Now fill the container and count how many handfuls it took. Using what you know about the number of pennies in a handful and how many handfuls it took to fill the container, calculate how many pennies are in the container.
- Count them out.
- Compare your estimate to the actual number of pennies.
- Repeat steps 1-6 with a different-sized container.
- Try to answer some of the Penny Fact Questions.
What to ask
- How close was your estimate?
- What is the largest number of pennies you can grab out of the jar?
- How many do you think a grownup can grab?
- Will a hand that is twice the size of yours be able to pick up twice as many pennies?
- What is a fast way to count your pennies?
What’s next?
- Trace your hand (fingers together) on a piece of paper. Cover the tracing of your hand with pennies. Use your hand to figure out how many pennies it would take to cover a tabletop.
- About how many hands would you need to hold 1000 pennies? How much money would that be?
- Try the same activity with different coins, like nickels. How does this change your estimate?