Give students a worksheet with pictures of things found on or near your playground. Ideas for pictures include swings, trees, basketball hoops, school doors, windows, benches and flowerpots. Have students think about their playground, then write down estimates for how many of each object may be outside. Talk about what makes a reasonable estimate, such as 10 swings, not 1,000 swings. After students make their estimates, go outside and take a real count. Compare their estimates to actual counts.
Play "The Estimation Game" with kindergartners. Pose questions for students to make predictions about, then take time to find the real answer. For example, "Who is the tallest student in class?" Have students make a prediction, then have everyone stand up to be measured. Try other quick estimations, such as who has the smallest hands, which pumpkin weighs the most or how many stars students can draw in one minute.
Get a clear plastic jar or container with a lid. Fill the jar with one type of item. Sample items include plastic frogs, interlocking cubes, individually wrapped candies, pasta wheels or cotton balls. Show students the jar. Hand out small scraps of paper for kindergartners to write down their estimations. Collect guesses. Count the number of objects together. Look through the estimates to see who came the closest to the actual count. Each week, have a student take home the estimation jar to fill and bring back to class to count.
Read "How Big is a Foot?" by Rolf Myller. Discuss how the king used his foot size to estimate how big to build the queen's bed, but the apprentice used his foot size when building the bed. The difference was two very different bed sizes. Have students use their feet to estimate the length of objects around the room. Hand out a worksheet with the names of objects, such as a table, chalkboard, friend or the entire room. Have students walk heel to toe like the king and apprentice did to make estimates using their foot size. Complete the activity yourself. Bring students together to compare measurements. Was everyone's answer the same or were there differences?
Print off two pictures of a fun, colorful monsters. Laminate pictures and tape them to large craft sticks. Introduce students to "Monster Number Squeeze." On a piece of scrap paper, write a number between 0 and 50, but don't show the class. Invite two students to be the monster number squeezers. Using a classroom number line, have one student hold a monster over the 0 while the other student holds the other monster over the 50. Invite students to try and guess the number written on your paper. Encourage students to make estimates to narrow down the possible numbers choices. For example, a student may ask, "Is the number bigger than 20?" If the number is bigger than 20, say "Yes, the number is bigger than 20." Have the person holding the monster over the 0 move up to 20. If not, say, "No, the number is smaller than 20." Then the student holding the monster over 50 should move down to 20." Announce, "The monsters are squeezing in on my number!" Continue calling on students to make estimates and squeeze down the possible number choices. When students get close to the actual number, have them switch to making exact guesses. The winner can select the secret number for the next round.