Unit 1
Numbers.
The foundations: negative numbers, fractions and decimals, percentages, and the order of operations with powers and roots.
The unit, lesson by lesson
Lessons
4 lessons · 21 practice questions · about an hour
Negative numbers on the number line
Adding and subtracting as jumps along the number line, which way you go when you subtract from a negative number, what subtracting a negative does, and which negative number is greater.
Fractions and decimals
What a numerator and a denominator say, how a fraction becomes a decimal, why fractions are added only over a common denominator, and how to compare decimals.
Percentages
A percentage is a part per hundred: how to find a percentage of an amount, why a discount is a multiplication, and why a fifty per cent rise and a fifty per cent fall do not bring you back to the start.
Order of operations, powers and roots
The order in which an expression is worked out: brackets, powers and roots, multiplication and division, and last addition and subtraction. What a square and a square root are, and why minus three squared is minus nine.