Find an area with leaves pile of preferably dry leaves. Dry leaves are easier to rake, are less messy and more fun to play with at the end. If leaves are scattered across a lawn, mark out with string or some 'marker' the area you want to estimate. You can even use students to make for corners in a square surface area. Have each student make an initial estimate individually of the leaves. (Write these down so you can average afterwards). Now ask students how they came up with their estimate? Discuss ways to make the estimate more accurate - such as counting the leaves in small area and multiplying to make up a larger area. Redo estimates. Take an average. If time (and enough helpers) rake the leaves up and make an actual count to compare. Put leaves into piles of 10s, 100s, and 1000 at the end. Note: Do not make the area too large. For those at home, afterwards you can continue to complete the chore of raking the lawn and estimate the number of leaves in bag. Then you can figure out a good approximation for how many in the yard by counting the bags collected.