Dilations in the coordinate plane

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.

• What Moved the Points? — Cut & Glue Sort 25 minutes · 5 sheets

  12 pieces — rules, points with their images, and segments drawn with their images — sorted into a dilation with center the origin, a dilation with another center, or not a dilation at all: the translation rule that adds the scale factor, two points with one number multiplied, and a pair that only looks like a dilation.

• Dilations: Where Is the Center? — Answer Maze 10–15 minutes · 4 sheets

  8 boxes on one page: dilate a point about the origin and about another center, undo a dilation, find the center from two points and their images, and find the image of a line when the center is on it and when it is not — a wrong answer goes to a box that sends the student back, and the row of box numbers at the bottom is the check.

• Dilations: Is That the Image? — Mystery Picture 25–35 minutes · 4 sheets

  25 squares, each a small grid with a center, a point and a point marked as its image, and a scale factor: fill the square if that is the right image. The wrong ones use the origin’s rule about another center, forget to add the center back, add the scale factor, or sit on the right line at the wrong distance — and when every square is right, a picture appears.

• Dilations in the Coordinate Plane — Scavenger Hunt a full class period · 13 sheets

  16 cards around the room: dilate a point about the origin or about another center, with the scale factor given as a number, as a distance or in a rule, and undo a dilation — every answer is a point, a wrong answer lands on a card that sends the group back, and a clean run is 8 lines on the record sheet.