Gather a variety of household items such as paper clips, cotton balls, toy blocks and dry beans. Include items of varying size, shape and weight.
Place small amounts of each item into a plastic bag. Vary the amounts so that some bags appear very full and other bags appear more empty.
Create a display to show the kids the items in their bags and introduce the word estimation. Ask the children what they think the word might mean. After getting a variety of answers, explain the definition of estimation. Ask why someone might want to estimate the contents of the different bags instead of counting them.
Show the children how you would estimate the number of items that are in two of the bags. An easy way to model for them is by thinking aloud. Choose two bags that have items that are different in size. By thinking aloud, explain how you would arrive at a guess for each bag.
Tell students to write an estimate for the number of objects in each bag. Encourage them to share their thinking out loud with you or with a classmate
Assign groups of students to count the number of items in each bag and record the information.
Compare the count of the items to the students' estimates. Ask students why the numbers may have varied and how to make estimates more accurate in the future.