Same Shapes Match Slides
Math Grade 8 • Lesson 11
Unit 1: Shapes
What Is the Same?
Let's look at shapes that match!
A
B
Same size. Same shape. Perfect match!
Today's Goal
"I can tell if two shapes are the same."
1
Same Size
2
Same Shape
Say it: "These two shapes match!"
New Math Word
Congruent
Say: kon • GROO • ent
Same size
Same shape
They fit on top!
Congruent means exact match.
A B Shape A is congruent to Shape B!
Read: "Shape A and Shape B are congruent."
Warm-Up Activity
Look at Your Hands!
Try It Now 🤲
1
Put your hands together.
2
Palm to palm. Fingers match fingers.
They fit right over each other!
Are your two hands the same?
👍 Same size? YES
👍 Same shape? YES
🪞 Mirror image? YES (Flipped!)
Your left hand and right hand are congruent! They are mirror images.
Find the Match
Left Hand or Right Hand?
Left Hand Thumb sticks OUT
Right Hand (Mirror) Flipped across the line!
Can you turn your left hand to become your right hand? NO, you must FLIP it!
How Shapes Move
3 Ways to Move Shapes
1. Transform
Move straight
(Slide)
2. Rotate
Spin around
(Turn)
3. Reflect
Flip like mirror
(Flip)
Moving a shape does NOT change its size or shape!
Activity 2
Are They Congruent? (Case 1)
Pair A
Shape 1
Shape 2 (Turned)
YES! They are Congruent!
Shape 2 is just turned. If you turn it back, it fits exactly!
Sentence Starter:
"They are congruent because they have the same size and same shape."
A shape can point in a different direction and still be congruent!
Activity 2
Are They Congruent? (Case 2)
Pair B
Shape 1 (Square)
Shape 2 (Slanted)
NO! NOT Congruent!
They do NOT match. One is a square. One is slanted. They will not fit on top.
Sentence Starter:
"They are not congruent because they have a different shape."
If they do NOT fit exactly on top, they are NOT congruent!
Activity 3: Two Math Clues
Inside and Around
Area Inside
Count the squares inside the shape.
1
2
3
4
5
6
Area = 6 squares inside
Perimeter Outside
Count the steps around the outside edge.
Top: 3 steps ➔
2 ⬆️
•
•
•
•
•
•
⬇️ 2
⬅️ Bottom: 3 steps
Perimeter = 3 + 2 + 3 + 2 = 10 steps around
Congruent shapes must have the SAME Area and the SAME Perimeter!
Think and Compare
Are These Congruent?
Rectangle R (3 by 2)
Area = 6 squares
Perimeter = 10 steps
Rectangle C (6 by 1)
Area = 6 squares (Same!)
Perimeter = 14 steps (Different!)
Do they match? NO! They are NOT congruent!
They have different shapes!
Review & Check
How to Check for Congruent
✓
Check 1: Same Shape
Do all the sides and corners match?
✓
Check 2: Same Size
Is one bigger or smaller? (Must be the exact same!)
✓
Check 3: Can you Slide, Turn, or Flip?
Can you move one shape so it sits right on top?
If all 3 are YES ➡️ The shapes are CONGRUENT!
Cool-Down
Mirror Match
Your Turn
line ℓ A B Shape B is flipped across line ℓ
Are Shape A and Shape B congruent?
(Hint: Does flipping change the size or shape?)
Fill in the blank:
"Yes! They are congruent because flipping does not change their size or shape."
🎉 You learned a big 8th grade math word: CONGRUENT! Great Job! ⭐
Box Counting Practice Worksheet
Math Grade 8 • Unit 1 • Lesson 11
Area & Perimeter Box Method
Name:
Date:
1
2
3
4
5
6
Area (Inside) Count the boxes inside: Area = 6
3
2
2
3
Perimeter (Around) Add the outside steps: 3+2+3+2 = 10
Problem 1: Square Shape 2 boxes wide • 2 boxes tall
A. Area (Inside): Write numbers 1, 2... in the boxes above.
Area =
boxes
B. Perimeter (Around):
Top:
+ Side:
+ Bottom:
+ Side:
=
Problem 2: Rectangle Shape 4 boxes wide • 2 boxes tall
A. Area (Inside): Count all boxes inside.
Area =
boxes
B. Perimeter (Around):
=
💡 Remember: Area is INSIDE boxes. Perimeter is AROUND the edge! • Page 1 of 2
Box Method Practice & Congruence Match Page 2
Problem 3: Long Strip 5 boxes wide • 1 box tall
Area (Inside):
boxes
Perimeter (5+1+5+1):
steps
Problem 4: 3 × 3 Square 3 boxes wide • 3 boxes tall
Area (Inside):
boxes
Perimeter (3+3+3+3):
steps
🌟 Challenge: Are They Congruent? Turn & Match
Shape A (3 × 2)
Area: 6 boxes
Perimeter: 10 steps
Shape B (2 × 3)
Area: 6 boxes
Perimeter: 10 steps
Can you rotate (turn) Shape B so it fits exactly on top of Shape A?
YES (Congruent!)
NO
How do you feel about the Box Method?
😃 I got it! 😐 Need a little help 🤔 Need more practice