Symmetry

Objectives

To look at a shape and to identify any lines of symmetry.

To understand the connection between symmetry and mirror reflection.

Resources

Abacus 4 Textbook 2 | Small hand mirror with a straight edge | Lines of Symmetry using a Mirror (YouTube)

Today's Lesson

Main Activity

For a mental warm up at the start of the lesson, ask your student around 20 simple division calculations within, or just beyond the times tables; some with remainders, e.g. 27 ÷ 9, 42 ÷ 3, 54 ÷ 5, 78 ÷ 6 etc.

Turn to page 38 in Abacus 4 Textbook 2.

Watch 'Symmetry' to recap lines of symmetry in a shape.

Look at the diagrams with your student. Ask them which lines can have the mirror placed on them to be able to complete the image of the shape in the reflection of the mirror. The mirror line is called the line of symmetry. Watch Lines of Symmetry using a Mirror (YouTube) to see how a mirror can be used to find lines of symmetry. When the mirror is on the line of symmetry, the shape will look correct by looking in the mirror.

If a shape is folded in half along a line of symmetry, each side should match exactly, like a butterfly. Ask your student to look carefully at the first shape and to think carefully about each line. Which lines could the shape be folded down so that each point and line match up with the opposite side perfectly?

Once your student has decided which lines are lines of symmetry and which are not, allow them to check with the hand mirror.

Ask your student to complete the page.

Turn to page 39 in Abacus 4 Textbook 2.

Scan or copy the top half of the page, so your student can draw directly on the paper.

Ask your student to draw the symmetrical opposites of each shape. If it becomes necessary, allow your student to use the mirror, as the shapes along angled lines of symmetry can be a bit tricky.

Look at the bottom half of the page and ask your student to describe each shape that has been asked for. Ask your student to draw each shape and to mark in the lines of symmetry, as specified.

Citations

[1] www.youtube.com [2] www.youtube.com