One step at a time.

We are finding a rule for a line. Two points tell us its slope. One of those points then helps us find its y-intercept.

1. Read two points. Each point is written (x, y): horizontal position first, vertical position second.
2. Find the slope, m. Compare the change in y with the change in x.
3. Find the y-intercept, b. This is the y-value at x = 0.
4. Write the equation and check. Use the other point to test the rule.

The four buttons at the top match the four steps on the front of the student paper. Use Next to reveal one idea. Nothing advances to the next idea by itself.

For families: try a step before revealing it. Ask, “Which number goes here, and why?” The extra examples use the same method as the paper.

Open the two-sided student paper ↗

Keyboard: ← / → back / next · R replay · Space pause motion · F full screen