Algebra

Algebraic expressions

A letter stands for a number you do not know yet or that can change. You calculate with it just like with numbers: collect like terms, expand brackets, substitute values.

Lower secondary (years 1-2)Ages 12 to 14Draft: Not yet checked by a maths teacher.

What you need first

Order of operations

Why

An ice cream costs 2 euros per scoop plus 1 euro for the cone. How do you write the price for any number of scoops?

You could make a table for 1, 2, 3 and 4 scoops, but it is never finished. With a letter you catch every case in one line: call the number of scoops b, and your ice cream costs 2b+1 euros.

To find out what 3 scoops cost, you put in b=3: 2×3+1=7 euros. The formula works for any number.

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