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Grade 3 · Math · Unit 7 of 15

Patterns & Equations

Pattern rules and mystery numbers

What your child practises

Extending increasing and decreasing patterns, describing pattern rules in words and tables, and solving one-step equations like ☐ + 8 = 23.

Ontario Curriculum expectation: C1.1–C1.4, C2.2, C2.3 · patterns, and equal and unequal expressions

How we explain it

Children can open this short lesson before they practise.

  1. An equation has an = sign. Both sides are the same.
  2. A letter or box stands for a missing number.
  3. Do the opposite to find it: the opposite of + is −.

Example: n + 7 = 15 Undo + 7 by taking away 7. 15 − 7 = 8. Answer: n = 8

Sample questions

A taste of this unit. In the app, questions change every time and get easier or harder to match your child.

  1. Question 1

    What number goes in the box?

    74 − = 19

    • 93
    • 55
    • 54
    • 56
    Show answer

    55

    Hint: What do you take away from 74 to leave 19? Count up from 19 to 74: 55.

  2. Question 2

    Follow the pattern. What number goes where the ? is?

    CarsWheels
    14
    28
    312
    416
    5?

    answer box

    Show answer

    20

    Hint: Each row has 4 more wheels. Keep adding 4: 16 → 20.

  3. Question 3

    What number goes in the box?

    48 + = 57

    • 9
    • 10
    • 8
    • 105
    Show answer

    9

    Hint: Count up from 48 to 57, or think 57 − 48 = 9.

  4. Question 4

    What number is missing from the pattern?

    9, 13, , 21, 25

    answer box

    Show answer

    17

    Hint: The numbers go up by 4 each time. 13 + 4 = 17.

  5. Question 5

    Which pattern rule fits?

    225, 200, 175, 150

    • Start at 225 and subtract 50 each time
    • Start at 225 and subtract 25 each time
    • Start at 225 and add 25 each time
    • Start at 200 and subtract 25 each time
    Show answer

    Start at 225 and subtract 25 each time

    Hint: The pattern starts at 225. Then it changes by the same amount each time: 225 to 200 is −25.

  6. Question 6

    Which equation matches the story? The is the number we don't know.

    Sofia had 97 marbles.

    Sofia gave some to friends.

    Now Sofia has 59.

    • 97 − ☐ = 59
    • ☐ − 97 = 59
    • 97 + 59 = ☐
    Show answer

    97 − ☐ = 59

    Hint: Sofia started with 97 and gave some away, leaving 59. So 97 − ☐ = 59.

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