Day 3 facilitator guide: Slope and representations
Before class
Optional graph paper. Pearson 15486 is an optional slope supplement; the lesson is self-contained if the interactive is unavailable. Keep x and y units visible.
30-minute facilitation
| Minutes | Facilitation |
|---|---|
| 0–3 | W1 asks for slope; W2 asks for the y-intercept. Note students who divide y by x instead of comparing changes. |
| 3–10 | Model slope as change in y divided by change in x. Explain that y-intercept means the output at x = 0. |
| 10–14 | Work G1–G2; label both coordinate changes before calculating. |
| 14–22 | Students complete P1–P4. Discuss a vertical line only after students have tried it. |
| 22–27 | Collect E1–E2 independently. |
| 27–30 | Students explain the units of a slope in one sentence. |
Listen for
- Reversing one subtraction order but not the other.
- Using y/x for points on a line with a nonzero intercept.
- Calling a vertical slope zero: contrast division by zero with zero rise on a horizontal line.
- Treating an initial amount as a rate.
Support and extension
Support: draw horizontal and vertical arrows between two points and annotate their changes. Extension: find an equation through (2, 9) and (5, 18). Slope is 3 and intercept is 3, so y = 3x + 3.
Next action
E1 checks negative slope; E2 checks initial value versus rate in context. A student who computes correctly but cannot interpret units needs a context example.