Can you really captivate your whole class with an ear of dried corn? Yes, if it's the Estimation Ear.

 Hi All,

 It's that time of year when dried corn makes an appearance in supermarkets and farm stands, in fall and Halloween displays, and even on front doors. You might want to bring an ear into your classroom and try an estimation event with it.

Have students sit in a circle, ideally with each person having a white board and marker. Pass the ear of corn around so everyone gets a good look at it.  Have students describe what they see as far as structure, color, feel, etc. Use four senses (no taste!)

Ask students if they noticed how the ear is made up of separate kernels of corn. Then ask if they could estimate how many kernels there are on the whole ear. Give students an opportunity to think and write an answer.

Share the estimates, writing them down the estimates on the board and pointing out the range from lowest to highest. Now ask, is there anything about the ear of corn that they would want to know, that would help them make an even more accurate and confident estimate. For example, one thing that would be helpful would be to know how many kernels are in a row. Another thing would be to know how many rows there are. 

Have a volunteer come up and count the number of kernels in a row. Have a second person count and verify it. With this new information, ask students if they would like to revise their estimates. (By the way, these numbers can vary greatly depending on the size of the ear you use and of course, the size of the kernels.) Write these new estimates on the board and show the range. Ask how this new bit of information impacted their estimates.

Now take a permanent marker and mark a dot on the first kernel in any row. Have someone come up and  beginning with the dotted row, count all the rows as you turn the ear. Write this new information on the board. Ask students if they would like to revise their estimates again. Have students share their revisions and methods.

If you want to take this a step further you can actually remove the kernels from the cob, split them into groups and into cups, and  then give these out to partners. Partners can do a physical count, put that number on the board and then invite the class to add up all of the numbers together to arrive at a final, accurate count.

Remind students throughout that estimates are "thinking guesses," not random, lucky guesses or exact counts. Estimates are also supported by what we can know or find out about an amount. Even partial knowledge can helps us make a better estimate. Participating in this activity helps reinforce these ideas.

All the best,

Bob