Teaching Estimation

 

The toughest part about teaching estimation is the concept of reasonableness.  The goal of estimation is not randomness, but an approximation of a close answer.  The best way to help students understand what a 'reasonable response' would be is to have many, many concrete examples of estimation that students can relate to and understand.
I use the CPA method when I'm introducing new math concepts.  It's been popularized by Singapore Math enthusiasts.  Basically, the idea behind it is that each time you teach children to embrace a new math concept, you start with something concrete that they can touch and feel, then move to a picture of the same types of things they've been working with, and last move to an abstract concept like writing about their math knowledge.  My students have really thrived in math, since embracing this style.  I first heard of it at an SDE training many years ago with my math teaching IDOL, Catherine Kuhn.  I could probably write a book on how this woman revolutionized math for me when I taught third. #seriously Imagine my surprise to find that she's also written books for primary. #winning
Her latest book has some great ideas on numerology, and I'll be doing quite a bit with her estimation section this year.  CHECK THIS OUT! #forreal
The thing I like best about Catherine is that she has such great ideas for a hands on approach to math.  That's your C:concrete.



Have you ever heard of Bruce Goldstone?  He's my new estimation bestie! :)  #realtalk

This book has the BEST pictures! :)  Kids love looking at them! :)  Bruce uses these AMAZING pictures to help kids conceptualize numbers.  Using this book in your classroom would be a great way to introduce P:pictorial representation to your students.

The last thing is A:abstract
For this, you'll want students to record their findings and look for patterns.

One of the things I learned to embrace while learning from Catherine is to have a hook!  In her classes, she loves to work with FOOD! :) The kids love it, and then after...sometimes, they'll even get to eat it.  Once I feel like my students can really embrace estimation, we finish up with this activity.  You'll need baggies of skittles with 20 skittles per bag.  You should have enough baggies that each team of two in your class can have their own. You'll need pencils and recording sheets.
Show the students your bag of skittles.
Ask them to predict..without counting...how many of each color of skittle there are.
Next, record those guesses.
Sort out your skittles by color.
Record how many of each color there ACTUALLY were.
Discuss with the students what kinds of strategies they used to come up with their approximations.
Then, send them out to try it on their own.

Give it a go with your kids!  If you want this quick worksheet, designed to go with regular Skittles, please click HERE.