Concept 4 of 6
Comparing Lengths
Today's big idea
Measure each, then the bigger number is longer.
12 cm beats 9 cm, so that pencil is longer.
How it works
👀 What's going on?
Which pencil is longer? Measure both and compare.
💡 Here's the trick
To compare lengths, measure each one, then the bigger number is longer. Line them up at the same start to see it.
Pencil A is 12 cm and pencil B is 9 cm. 12 is more than 9, so A is longer.
✍️ Try it
A ribbon is 8 cm and a string is 11 cm. Which is longer? → the string.
⚠️ Watch out
Only compare the numbers if both lengths use the same unit.
Watch me solve one
Quanta solves it
“Watch how I think through one of these — then you try.”
THE PROBLEM
“Put 6 cm, 10 cm and 8 cm in order, shortest first.”
- 1
Find the shortest
6 is the smallest number, so 6 cm first.
- 2
Then the rest
8 comes before 10.
- 3
Answer ✓
6 cm, 8 cm, 10 cm
Now you try one — same steps, different story 👇
See it in action
⚡ Time to play!
Tap the longer one.
Quick check
✅ VERIFICATION
Which is the longest?
⚡ Finish the activity above first to answer.
Keep going!
Up next: Length Word Problems
Tie lengths to add, cut them to subtract.