Give this before the unit. It doesn't test the new standards (7.G.A.1 and 8.G.A.4). It checks the grade 5, 6 and 7 skills they build on, so you can see who is ready and what to review first. It isn't meant to be graded. The answer key, with what each part tells you and how to reteach it, prints on its own page after it.

Pre-Assessment: Getting Ready for Similar Figures

Grades 7–8 · Checks earlier skills: 5.NF.B.5, 6.RP.A.1, 6.RP.A.3, 6.EE.B.7, 7.RP.A.2

Name

Date

Part A: Ratios 6.RP.A.1, 6.RP.A.3

1. A lemonade recipe uses 2 lemons for every 3 cups of water. Write the ratio of lemons to cups in two ways.

2. Complete the table of equivalent ratios.

lemons	2	4		10
cups	3		12

3. What do you multiply the first column by to get the last one?

How sure do you feel? Not yet A little I've got it

Part B: Scaling 5.NF.B.5

4. Without multiplying, circle bigger or smaller than 8:

8 × 3 bigger / smaller
8 × ½ bigger / smaller
8 × 1 bigger / smaller / same

5. A photo 4 inches wide is enlarged 3 times. How wide is the new photo?

6. On this map, 1 cm stands for 5 km. Two towns are 3 cm apart on the map. How far apart are they really?

How sure do you feel? Not yet A little I've got it

Part C: Same shape? 5.NF.B.5, 6.RP.A.3

7. Rectangle A is 2 by 4. Rectangle B is 3 by 6. Rectangle C is 3 by 4. Which two look like the same shape, just a different size? How do you know?

and because

How sure do you feel? Not yet A little I've got it

Part D: Equations and proportions 6.EE.B.7, 7.RP.A.2

8. Solve: 3x = 21

x =

9. Solve: x ÷ 4 = 5

x =

10. Solve: ²⁄₃ = ^x⁄₁₂

x =

How sure do you feel? Not yet A little I've got it

Answer Key: Pre-Assessment

Getting Ready for Similar Figures · for the teacher

Any two of 2 : 3, 2 to 3, 2/3
Table: lemons 2, 4, 8, 10; cups 3, 6, 12, 15
× 5
bigger; smaller; same
4 × 3 = 12 in
3 × 5 = 15 km
A and B: every side of B is 1.5 times the matching side of A (2 × 1.5 = 3, 4 × 1.5 = 6). C is not: 3 ÷ 2 = 1.5 but 4 ÷ 4 = 1.
x = 7
x = 20
x = 8 (2 × 4 = 8, 3 × 4 = 12)

What each part tells you

Part	Why it matters for this unit	If many students miss it
A: Ratios	Similar figures are all about equal ratios between matching sides.	Review ratio tables with Proportional Plates.
B: Scaling	A scale factor is a multiplier: more than 1 enlarges, less than 1 shrinks.	Enlarge and shrink a photo on a phone or projector and measure it.
C: Same shape?	#7 is the test for similar rectangles: the same multiplier for every side.	Draw rectangles on grid paper and compare them by multiplying, not adding.
D: Equations	Missing sides are found with equations like 3x = 21 and proportions like 2/3 = x/12.	Review with Tip the Scales.

Reading the results: a student who says C matches A (“it’s only 1 wider”) is judging by looks or by adding, not multiplying; that's the key misconception this unit fixes, so address it on day one. Compare the “How sure do you feel?” circles with the answers: a student who circles “I've got it” but misses the part is worth a quick conversation.