How Much Longer?

Compare two lengths and find the difference.

10 problems · about 12 minutes · 2.MD.A.4

What this lesson teaches

The child finds how much longer one object is than another, giving the answer with its unit.

From earlier lessons. Loosen up before the new work.

3 problems

Review — Estimating Length: About how long is one big step?
Answer About 1 metre.
Why A big step is roughly a metre.
Review — The Same Object, Two Units: Which gives the bigger number, centimetres or metres?
Answer Centimetres.
Why Smaller unit, bigger number, same length.
Review — Inches and Feet: How many inches are in a foot?
Answer 12
Why 1 foot = 12 inches.

Straightforward practice. Get the method working first.

3 problems

A 16 cm rope and an 11 cm rope. How much longer is the first?
Answer 5
Why 16 − 11 = 5 centimetres.
What unit does the difference have?
Answer The same unit as the lengths.
Why Centimetres minus centimetres gives centimetres.
14 cm and 6 cm. How much longer is the first?
Answer 8
Why 14 − 6.

The same ideas with more to keep track of.

1 problem

Mixed problems. Work out what kind of question it is before you start.

3 problems

9 inches and 12 inches. How much shorter is the first?
Answer 3
Why 12 − 9.
Two Ribbons: A red ribbon is 15 cm and a blue one is 9 cm. How much longer is the red one?
Answer 6 cm
Why 15 − 9 = 6 centimetres.
Two Sticks: A stick is 18 cm. Another is 18 cm. How much longer is the first?
Answer 0 cm
Why There is no difference, so the answer is 0.