Sixth Grade · Math · week 7

Double number lines for ratios

Use a double number line to represent and solve ratio, rate, and percent problems.

A double number line has two number lines stacked together, lined up so matching points show an equivalent ratio - it is a picture of a ratio table stretched out in a row.

Mark the known ratio pair at matching tick marks on both lines, then keep the spacing even as you fill in more pairs.

Double number lines work well for percent problems too: one line runs 0 to 100 (percent), and the other runs 0 to the whole amount.

📋 For the teacher
Teach it (10–15 min):
  • Draw two straight lines, one above the other, with tick marks lined up like a ruler.
  • Fill in the "easy" landmarks first - 0, and doubling or halving the known pair - before tackling in-between values.
  • For percents, always put 0% to 100% on one line and 0 to the whole amount on the other.
  • Use the visual to estimate before calculating exactly - the picture should make the answer feel reasonable.
Talk about it:
  • How is a double number line like a ratio table?
  • Why do 0 and 100% always line up with 0 and the whole amount?
  • When would a double number line be easier to use than a table?

Mastery looks like: They construct a double number line for a ratio or percent situation and read equivalent values from it accurately.

Common stumbles: Misaligning the tick marks between the two lines; spacing marks unevenly so halfway points come out wrong.

See it visually

Interactive, spoken-aloud tools that show this idea in motion.

Number LineCount, add, subtract, and skip-count with animated hops and a friendly voice.try →
Homework for this lessonType it, write it with a stylus, or print it for pencil & paper.open →
Records attendance + 15 min of Math for this learner.
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