Math 8 Unit 1 Lesson 3: Grid Moves
Adapted from Open Up Resources https://openupresources.org/
What do you notice? What do you wonder?
Follow the directions below each statement to move the figure. Use vectors to show translations. A vector is a quantity that has magnitude (size) and direction. It is usually represented by an arrow.
In the applet below, translate triangle so that goes to .
In the applet below, translate triangle so that goes to .
In the applet below, rotate triangle counterclockwise using center .
- Select the Rotate around Point tool.
- Click on the figure to rotate, and then click on the center point.
- A dialog box will open; type the angle by which to rotate and select the direction of rotation.
- Click on ok.
Reflect triangle using line .
Are you ready for more?
The effects of each move can be “undone” by using another move.For example, to undo the effect of translating 3 units to the right, we could translate 3 units to the left. What move undoes each of the following moves?
Translate 3 units up
Translate 1 unit up and 1 unit to the left
Rotate 30 degrees clockwise around a point P
Reflect across a line l
Lesson 3 Summary
When a figure is on a grid, we can use the grid to describe a transformation. For example, here is a figure and an image of the figure after a move.
Quadrilateral ABCD is translated 4 units to the right and 3 units down to the position of quadrilateral A'B'C'D'.
A second type of grid is called an isometric grid. The isometric grid is made up of equilateral triangles. The angles in the triangles all measure 60 degrees, making the isometric grid convenient for showing rotations of 60 degrees.
Here is quadrilateral KLMN and its image K'L'M'N' after a 60-degree counterclockwise rotation around a point P.
A second type of grid is called an isometric grid. The isometric grid is made up of equilateral triangles. The angles in the triangles all measure 60 degrees, making the isometric grid convenient for showing rotations of 60 degrees.
Here is quadrilateral KLMN and its image K'L'M'N' after a 60-degree counterclockwise rotation around a point P.
Lesson 3 Cool Down: Some are Translations and Some Aren't
Which of these triangles are translations of Triangle A? Select all that apply.