Unit 2
Ratio and scale.
Comparing amounts by multiplying: ratio and proportion, converting units, scientific notation, and orders of magnitude.
Before this unit
The unit, lesson by lesson
Lessons
4 lessons · 21 practice questions · about 2 hours
Ratios
A ratio compares two amounts by multiplying: how to scale a recipe up without changing it, how to simplify a ratio, and how to find a missing amount through the amount for one.
Converting units
Converting a unit is a fixed ratio: kilometres to metres, hours to minutes, metres per second to kilometres per hour, units of area, and the scale of a map.
Scientific notation
How to write very large and very small numbers with powers of ten: what the power counts, what a negative power means, and how to tidy the number in front.
Orders of magnitude
From an atom to the Milky Way in powers of ten: the order of magnitude of a thing, how many times bigger one thing is than another, and how many orders of magnitude lie between the smallest and the largest.