## CHAPTER 5: 2D GEOMETRY

**Lesson 5: Communicating About Symmetry **

**Goal**

Describe symmetry in 2D shapes.

**Instructions for Use**

**Symmetry Sort** allows students to test their knowledge of symmetry.

To use Symmetry Sort, click on “bounce back” There will be three circles on the page – “no lines of reflective symmetry”, “1 line of reflective symmetry” and “ 2 or more lines of reflective symmetry”. Look at each shape on the screen carefully and decide which circle it belongs in. Drag it into the circle. If you are correct, it will stay there. If not, it will bounce back and you can try again. When you are finished, click “Print” to print out your page.

**Reflective Symmetry** allows students to demonstrate reflective symmetry.

To use Reflective Symmetry, click on each shape to see where the line of symmetry occurs. When you have clicked on every shape, click on the “2” at the bottom of screen. There are three boxes – “Horizontal”, “Vertical” and “Both”. Drag each of the shapes below the boxes into the right box, depending on where the line of symmetry falls. If you are correct, the shape will stay in the box and a line will appear over it, showing you the symmetry. If not, the shape will bounce back and you can try again.

If you need to make the screen bigger, hold down the “Ctrl” button on your keyboard and scroll with the scroll bar on your mouse.

**More About Symmetry ** allows students to place lines of symmetry on various shapes.

To use More About Symmetry, read the instructions and then click on “recording sheet” on the third line to print out the recording sheet for the activity. Click on “Vertical” or Horizontal” and then click “New Figure”. Place your mouse cursor on the line that you see in the box – it will be on the left-hand side if you chose “Vertical” or at the top of the screen if you chose “Horizontal”. Drag the line to a place on the figure where you think it will make a line of symmetry. If you are correct, you will see a positive message on the screen. If not, you can move the line again.

After you have practiced on some vertical and horizontal figures, click on “Any”. Try to find the lines for eight more figures, keeping a record in the table on the recording sheet. Sometimes the line of symmetry will be horizontal, vertical or both. Write V for a vertical line or H for a horizontal line. If you are correct on the first try, write yes in the second line of the table and if not, write no. In the third line, write the number of tries you needed to place the line correctly.