Unit 3

Proportional Reasoning (the bridge to linearity)

Ratios, rates, unit rate, proportions, percents

This unit is about how two amounts move together: miles and hours, dollars and apples, a part and a whole. That one idea quietly runs the everyday world, from speeds to prices, and it sets up much of the algebra ahead.

It helps to have a little practice solving simple equations fresh in mind, along with some comfort working with fractions. If those feel far away, that's fine. You can pick them back up as you go.

Arithmetic asks "how much?" This unit asks a new question: how do two amounts move together?

When a car goes 60 miles every hour, you've found a steady rate: 60 miles for each single hour. That steady "so much for every one" turns out to be the seed of a big idea coming in Unit 5, called slope.

So take your time here. The same number you find in this unit will come back later wearing a new name, and seeing the through-line now makes that later idea feel familiar instead of new.

Before each new lesson, redo two or three problems from a lesson or two back from memory first. It's a small warm-up, and pulling the old work back from memory is what fixes it in place.