#### Math - 2019-20

# 2.12 - Symmetry

**The student will**

a) ** draw**
a line of symmetry in a figure; and

b) **identify**
and **create** figures with at least one line of symmetry

*Adopted: 2016*

### BIG IDEAS

So that I can recognize balance and symmetry in art and nature

So that I can understand that symmetry results in two equal parts of an object, animal, building, or picture

### UNDERSTANDING THE STANDARD

- A line of
symmetry divides a figure into two congruent parts each of which is the
mirror image of the other. An example
is shown below:

Lines of symmetry are not limited to horizontal and vertical lines. - Children
learn about symmetry through hands-on experiences with geometric figures and
the creation of geometric pictures and patterns.
- Guided
explorations of the study of symmetry using mirrors, paper folding, and
pattern blocks will enhance students’ understanding of the attributes of
symmetrical figures.
- Congruent
figures have exactly the same size and shape.
Noncongruent figures do not have exactly the same size and shape. Congruent figures remain congruent even if
they are in different spatial orientations.
- While investigating
symmetry, children move figures, such as pattern blocks, intuitively, thereby
exploring transformations of those figures. A transformation is the movement of
a figure—either a translation, rotation, or reflection. A translation is the
result of sliding a figure in any direction; rotation is the result of turning
a figure around a point or a vertex; and reflection is the result of flipping a
figure over a line. Children at this level
do not need to know the terms related to transformations of figures.

### ESSENTIALS

**The student will use problem
solving, mathematical communication, mathematical reasoning, connections, and
representations to**

- Draw a line
of symmetry in a figure (a)
- Identify
figures with at least one line of symmetry, using various concrete materials
(e.g., mirrors, paper folding, pattern blocks) (b)
- Determine
a line of symmetry that results in two figures that have the same size and
shape and explain reasoning (a, b)
- Create
figures with at least one line of symmetry using various concrete materials (b)

### KEY VOCABULARY

*Updated: Aug 22, 2018*