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Estimation Jar


By Quynh Nguyen, Classroom Teacher

Remember the jelly bean guessing game? That was one of my favorite elements of the Minnesota State Fair. I entered every year and won once. 

Estimation is an essential skill, yet many do not see its value. When I ask the kids to estimate, they start writing down equations or want to count all the units in the jar. The most common answer I hear is, “I just want the right answer.” I talked to my 1-2s class about where I might use estimation: at the grocery store to see if I am under my budget, how many cupcakes might fit into a container, or to see how much time it might take me to bike from my house to work, etc. Estimation is practical. 

An activity that I wished I had done all year with my first and second graders is the estimation jar—I called it Estimation Station. I started this activity in the spring. Each morning the kids signed in with an answer to a daily question. For Estimation Station, I asked them to estimate how many Base Ten units are in the jar. They were free to pick up the jar but were not  allowed to open it to count the content inside. While many wanted to count, it became more fun to guess. During a circle later in the day, I emptied the jar and asked the kids to come up one at a time and grab ten units. We used the skills of counting and trading. After all of the units were claimed. I asked them to come and trade their ten units for a rod. And then, ten rods for a flat. When all the trading was finished, we placed the flats, rods and units on our trading mat. Someone read the total out loud. 

To find our winner, I had the kids help to compare the numbers and used subtraction to see who was closest to the actual number. The first student who won was a first grader. I asked them what they wanted as a prize and they said “a high five from everyone.” My class lined up and the winner went down the line and collected their prize. 

We repeated this activity many times that month, I kept the manipulative (Base Ten units) the same and varied the size of the jars. The kids got better at their estimating skills and we had a lot of fun together.