Letters for Numbers

Variables and expressions

An interactive lesson with 7 steps, about 6 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• A letter stands for an unknown or any number; 3n means 3 × n.
• An expression is a recipe; an equation is a claim with an equals sign.
• Substitute values in brackets, then follow the order of operations.

Steps

1. A number left blank
2. Words to symbols
3. One rectangle, many sizes
4. Substitution with negatives
5. Shorthand
6. A gym membership
7. Hours and minutes