The Problem Solving and Communication Activity Series Guess and Check

Guess and Check

The skills used to Guess and Check are essential for helping students build mathematical models and write equations. Getting good and guess and check is an important step on the way to algebraic reasoning. In that regard, Guess and Check is closely related to the Make a Table and Make a Mathematical Model strategies. Plus, careful, organized conjecturing and hypothesis testing is at the heart of what mathematicians do.

One other thing: when doing guess and check, never erase guesses that didn't work. If you do, how can you see patterns?

Activities to Learn this Strategy

Facilitation Questions

  • Is there a quantity you don't know that you could make a guess for?
  • What calculations could you do?
  • What constraints in the problem could you use to check if your guess worked?

Recommended Problems

The Strategy Examples documents linked from these problems contain examples of what students could do with the activities. You need a Class Membership or higher to access Library problems.


Counting Shells
Lining Up for Lunch
Yummy Gummy Bears

Math Fundamentals

Greta's Garden
Just the Facts
You Think Your Teacher is Tough!
Nuts in a Bowl


Kaytee's Contest
A Cranberry Craving
Caliyah's Cart
Two Heads are Better than One


Are You Ready for Some Football?
A Surprising Sequence
Eating Contest
A Championship Season


Congruent Rectangles
Trisecting a Square
Dilating a Quadrilateral
Triple Tango

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