Use Objects to Represent Unknowns — Math Worksheet for 8-Year-Olds (Early Algebra, Grade 3)

Free worksheet covering multiple subjects for age 8 students. Created with Learning Corner's AI-powered tools.

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Instructions

Some numbers are playing hide-and-seek! They have hidden behind different objects. Your mission is to use your math skills to figure out what number each object is hiding. Solve the mysteries below!

Part 1: Find the Secret Number

For each puzzle, find the number that the object stands for.

1.   8 + ★ = 15
The star ★ is the number _______________.
2.   20 - ♥ = 11
The heart ♥ is the number _______________.
3.   â–  + 6 = 18
The square â–  is the number _______________.
4.   14 - ● = 5
The circle ● is the number _______________.
5.   ♦ + ♦ = 16
The diamond ♦ is the number _______________.

Part 2: Two-Object Mysteries

First, solve for the first object. Then, use that answer to help you solve for the second object!

Mystery #1
First, solve this:   🍎 + 🍎 = 12
So, the apple 🍎 is the number _______________.

Now, use what you know to solve this:   🍎 + 🍌 = 15
So, the banana 🍌 is the number _______________.
Mystery #2
First, solve this:   🎈 - 5 = 10
So, the balloon 🎈 is the number _______________.

Now, use what you know to solve this:   🎈 - 🎁 = 7
So, the gift 🎁 is the number _______________.

Part 3: Secret Number Stories

Read the story, then find the secret number that the object stands for.

1. Leo had 9 toy cars. He got some more for his birthday. Now he has 17 toy cars! Let a 🚗 stand for the mystery number of new cars.

Equation: 9 + 🚗 = 17
The car 🚗 is the number _______________.
2. Maya baked 24 cookies. She gave some to her friends. Now she has 10 cookies left. Let a 🍪 stand for the mystery number of cookies she gave away.

Equation: 24 - 🍪 = 10
The cookie 🍪 is the number _______________.



Answer Key

Part 1: Find the Secret Number

  1. The star ★ is the number 7.
  2. The heart ♥ is the number 9.
  3. The square â–  is the number 12.
  4. The circle ● is the number 9.
  5. The diamond ♦ is the number 8. (because 8 + 8 = 16)

Part 2: Two-Object Mysteries

Mystery #1

  • The apple 🍎 is the number 6.
  • The banana 🍌 is the number 9. (because 6 + 9 = 15)

Mystery #2

  • The balloon 🎈 is the number 15.
  • The gift 🎁 is the number 8. (because 15 - 8 = 7)

Part 3: Secret Number Stories

  1. The car 🚗 is the number 8.
  2. The cookie 🍪 is the number 14.
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