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U n t er r i ch t spl a n
Line s o f Sy mme t ry
Altersgruppe: 4 t h Gr ade , 5 t h Gr ade
Virginia - Mathematics Standards of Learning (2009): 2.15 a, 2.15 b
Virginia - Mathematics Standards of Learning (2016): 2.12.a, 2.12.b
Fairfax County Public Schools Program of Studies: 2.15 .a.1,
2.15 .b.1, 2.15 .b.2, 2.15 .b.3
Online-Ressourcen: S ymme t r y L i ne s
Opening
T eacher
present s
St udent s
pract ice
Ext ension
Mat h
Pract ice
4
12
12
15
4
min
min
min
min
min
Closing
M at h Obj e c t i v e s
E x pe r i e nc e folding shapes in multiple ways
P r ac t i c e distinguishing between symmetric and asymmetric
shapes
L e ar n to identify lines of symmetry
De v e l o p algebraic skills
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Ope ni ng | 4 min
Display the following:
S ay: I wrote you a message, but I only wrote the top half. Let’s
pretend there is a mirror along the dashed line. Let’s draw the mirror
image under the dashed line so we can see the message clearly.
A sk a student to come to the board to draw the bottom half of the
message.
S ay: So now we can read the message. What does it say?
It says, “Hi.”
S ay: The letters “H” and “I” are symme t r i c . The dashed line is a
l i ne o f symme t r y . What does symmetric mean?
Symmetric means that a line can be drawn on a shape where one
half of the image is the mirror image of the other half.
S ay: The letters “A” and “D” are also symmetric. What is different
about the symmetry in “A” from the symmetry in “D”?
The line of symmetry for the letter “A” is vertical. The line of
symmetry for the letter “D” is horizontal.
S ay: Today we are going to look at some shapes and determine if
they are symmetric. If they are, we are going to find their line of
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symmetry.
T e ac he r pr e se nt s M at h game : S ymme t r y L i ne s - P o l ygo ns
| 12 min
Present Matific ’s episode S ymme t r y L i ne s - P o l ygo ns to the
class, using the projector.
The goal of the episode is to draw a line of symmetry (if it exists) on a
polygon.
E x a m p le :
S ay: Please read the instructions.
The instructions say, “Mark a symmetry line on the shape.”
A sk: What 2 buttons are possible to click once we have drawn our
line?
We can click the button that says “Done” or the button that says
“Impossible.”
Draw a random line on the shape. The shape will then fold over the
line you have drawn.
A sk: How can we tell if the line I have drawn is a line of symmetry?
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If the shape folds over exactly on top of itself, then the line is a
line of symmetry.
A sk a student to come to the front and draw an actual line of
symmetry. The student should draw the line and then click
. If
the student determines that no such line exists, the student should
click
.
If the answer is correct, the episode will proceed to the next problem.
If the answer is incorrect, the instructions will wiggle.
The episode will present a total of 5 problems.
S t ude nt s pr ac t i c e M at h game : S ymme t r y L i ne s - P o l ygo ns
| 12 min
Have the students play S ymme t r y L i ne s - P o l ygo ns and
S ymme t r y L i ne s - V ar i o us S hape s on their personal devices.
Circulate, answering questions as necessary.
E x t e nsi o n M at h P r ac t i c e : S ymme t r y L i ne s W o r kshe e t | 15
min
S ay: In this episode, we identified lines of symmetry. We were
asked to draw one line of symmetry. However, sometimes you can
draw more than one line.
Display the following shapes:
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A sk students to work in pairs. Have them copy the shapes onto
paper. They should draw all the symmetry lines they can find for
each shape. Then they should write down the number of lines of
symmetry that each shape has.
When the students are done working, share.
Ask a student to come to the board and draw 1 line of symmetry
on the star, if it can be done.
When that student is done, ask another student to come to the
board and draw a different line of symmetry on the star, if it can
be done.
Repeat until the students agree that no more lines of symmetry
can be drawn.
Record the number of lines of symmetry that exist.
Repeat for each shape.
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S ay: Symmetric objects appear in many places in real life. Perhaps
one of the most discussed symmetric objects is a snowflake.
Today, we’re going to make paper snowflakes. Real snowflakes have
6 lines of symmetry, so ours will too.
Enlarge and distribute the following circle:
Distribute scissors.
Display the following instructions:
1. Cut out the circle from the paper.
2. Fold the circle in half.
3. Fold the semi-circle into thirds, with a point at the center of the circle.
4. Cut! Cut out lots of shapes from all edges of the sector.
5. When done, unfold.
Circulate, answering questions as necessary.
When the students are done, collect the snowflakes to display later.
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C l o si ng | 4 min
Distribute a small piece of paper.
Say: Today, we have talked about lines of symmetry. We’ve already
looked at some letters, but we’re going to look at a few more.
Display the following letters:
Ask the students to copy the letters onto their small piece of paper
and draw all possible lines of symmetry.
Collect papers, to review later.
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