Writing equations of parallel and perpendicular lines
- What pins a line down — 3 tasks
- Point-slope form, built from the slope formula — 3 tasks
- Transform the slope before you place it — 6 tasks
- The two lines the formula cannot write — 3 tasks
- The perpendicular bisector — 3 tasks
- Practice — 23 tasks
- Summary — 2 tasks
- Cool-down — 3 tasks
Classroom activities
Things a class does rather than writes on. Each one is a finished PDF: print it, cut it up if it says so, and hand it round.
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Which Line Is It? Equations of Parallel and Perpendicular Lines — Cut & Glue Sort 25 minutes, including the cutting · 5 sheets
12 pieces, each a line described in words with one equation in the form y = mx + b. Students check the point and the slope and sort each piece: correct, wrong, or cannot tell because the words fit many lines. The wrong ones are the common mistakes, and the cannot-tell row shows what a line needs: a point and a slope.
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Equations of Parallel and Perpendicular Lines Through a Point — Answer Maze 10–15 minutes · 4 sheets
8 boxes on one page. Each asks for the line through a point, parallel or perpendicular to a given line, written as y = mx + b. The given line comes as an equation in several forms or through two points. The wrong answers are the common mistakes: finding b with the old slope, a half-done opposite reciprocal, keeping the old slope, a sign slip, swapped coordinates, or copying the given line's b. The row of box numbers at the foot is the check.
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Equations of Parallel and Perpendicular Lines: Is the First Line Right? — Mystery Picture 25–35 minutes · 5 sheets
25 squares, each naming a new line parallel or perpendicular to a given line through a point, with the first line of the work for b, such as 4 = −½(2) + b. Students solve nothing: they check that the new slope is used and that the point is put in the right places. Fill it or leave it white, and a picture appears.
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Equations of Parallel and Perpendicular Lines Through a Point — Scavenger Hunt a full class period · 13 sheets
16 cards around the room. Each asks for the line through a point, parallel or perpendicular to a given line, written as y = mx + b. The given line comes as an equation in several forms, through two points, or drawn on a grid. Finding b with the old slope, keeping the old slope, a half-done opposite reciprocal, a sign slip or swapped coordinates lands on a card that sends the group back. A clean run is 8 lines on the record sheet.