🔢 MathGrade 3Lesson 6
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Use Number Lines

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Learning Objectives

  • 1Locate and label whole numbers on a number line up to 1,000
  • 2Use a number line to model addition and subtraction by counting forward and backward
  • 3Determine the missing value when hopping a given number of steps on a number line
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Mini Lesson

A number line is a straight line with numbers placed at equal intervals. It helps us visualize numbers, understand their order, and model addition and subtraction. Hopping forward (to the right) means adding; hopping backward (to the left) means subtracting.

Adding on a Number Line

  • Find your starting number on the line.
  • Hop forward (right) the number of steps you are adding.
  • Each hop equals the size of the step — e.g. one hop of 10 moves you 10 places right.
  • Where you land is the sum: 30 + 20 = 50 (start at 30, hop +10 twice).

Subtracting on a Number Line

  • Find your starting number on the line.
  • Hop backward (left) the number of steps you are subtracting.
  • Where you land is the difference: 80 - 30 = 50 (start at 80, hop -10 three times).
  • Subtracting moves you to a smaller number — toward zero.
Hop forward on a number lineA number line from 0 to 50 with ticks every 10. Two forward hops of plus 10 each start at 10 and land at 30.Hop Forward (Adding)01020304050start+10+10land10 + 20 = 30Two hops of +10 from 10 lands at 30.
Hop backward on a number lineA number line from 0 to 50 with ticks every 10. Two backward hops of minus 10 each start at 40 and land at 20.Hop Backward (Subtracting)01020304050start-10-10land40 - 20 = 20Two hops of -10 from 40 lands at 20.
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Hopping right = adding. Hopping left = subtracting. Count the hops, not the spaces.

Vocabulary
Number line
A line with numbers placed in order at equal spacese.g. Find 12 on the number line.
Tick mark
A small line on a number line that marks each numbere.g. Each tick mark stands for 1.
Interval
The space between two tick marks on a number linee.g. On this line, the interval is 5.
Hop
A jump from one number to another on a number linee.g. Take 3 hops to the right to add 3.
Add
To put numbers together to find the totale.g. I add 4 + 3 by hopping right 3 times.
Subtract
To take one number away from anothere.g. Subtract 2 by hopping left 2 times.
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← Lesson 5: Identify Patterns in SequencesLesson 7: Estimate Sums and Differences →