estimation

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Archive : 2001 : March : 28

estimation
By Cathy-Dee

An activity I often use to teach estimation is to have a number of small zip lock bags that are numbered. In each bag is a number of items (I start first with up to 25 items in each bag and then increase numbers later when
we are learning about larger numbers).
I have enough bags for each student to have 1 bag plus at least 10 extra bags. Then I have a sheet of paper where they write their estimates. They must first guess or estimate their answer and write it with a coloured pencil. Then they can open the bag and count the object and write the actual count.
You have to really watch them during this

activity, because first graders hate to guess - they want to change their answer because they feel that guesses are wrong. I always emphasize that a guess is always right, but some guesses are closer to the actual count than others and as we practice we should be able to have our estimates closer to the actual count.

I demonstrate first with a couple of sample bags and show them how to write their guesses and actual counts as well as the number on their bag on their recording sheet. I also let them know they probably will not be able to do every bag today, but that they should try to get 5 bags finished. I have also precounted all the bags and have the answer key. I don't worry when marking if the actual counts are correct as long as they are quite close. Sometimes when the bags are being used by a number of students one or two items will fall out.

Hope this helps, feel free to email me if I wasn't clear or if you have any questions.