How Can You Use Real Life to Teach Estimation?

Since some of our students are struggling with estimation, I’m thinking of bringing in a few pictures, that might help put estimation in perspective.  While out today at the grocery store, I came across estimation.

The sign said, “About 15 items.”

Oh, my gosh!  What does that mean?  I have 21 items in my cart!  Can I still go through the line?  The cashier looks haggardly and tired.  Is 15 about 20?  Is 21 about 20?

I think I will be okay going through the line with 21 items and without a fuss :).  Smooth sailing!

Then I found estimation again on a can of almonds.

The can displayed, “About 28 nuts.”

I’m on a diet.  Does that mean I can have 45 for the same calories?  No, I don’t think so.  I think that 45 is close to 50.  I know that 25  doubled would be about 50 and 28 is close to 25.  What about 30?  Would 30 be about 28?  Yes, 28 is only 2 away from 30.  I think I could have about 30 nuts for the same amount of calories!

I’m on a diet to teach estimation!

Having conversations like this reasoning about numbers will be my plan for this week!