# Expressions & Equations

January 9, 2020

## Puzzles: Mobile Puzzles

Mobile puzzles are pictorial representations of systems of equations; each beam that balances two sets of objects (representing variables as unknown “weights”) represents an equation. Children […]
December 3, 2019

## Difference of Squares

This page describes one silent teaching activity that serves, at the superficial level, to give students useful practice with multiplication facts, but that also builds deeper […]
November 21, 2019

## Order of Operations

Reducing ambiguity by agreement In general, nobody wants to be misunderstood. In mathematics, it is so important that readers understand expressions exactly the way the writer […]
November 21, 2019

## Puzzles: Who Am I Puzzles

Who-Am-I? puzzles give clues about some mathematical object — usually a number or a shape — and you are to figure out what the object is. […]
November 21, 2019

## Measurement: Discovering formulas for area

Area formulas Students who have the informal notion that area is the “amount of 2-D ‘stuff'” contained inside a region can invent for themselves most of […]
November 20, 2019

## Algebraic Thinking

Number tricks are fun for children. The fun, all by itself, is valuable, but is not mathematics. But understanding how the trick works is good mathematical, often algebraic, learning.