Cogito
Grade 2 Math · Chapter 2 · Lesson 7
Length Word Problems
Stories about how long things are.
10 problems · about 13 minutes · 2.MD.B.5, 2.OA.A.1
What this lesson teaches
The child solves add-to, take-from, and compare word problems about length within 100.
- Joining lengths means adding.
- Cutting a length means subtracting.
- Only add lengths in the same unit.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
3 problemsReview — How Much Longer?: A 16 cm rope and an 11 cm rope. How much longer is the first?
Answer 5
Why 16 − 11 = 5 centimetres.
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.
Warm Up
Straightforward practice. Get the method working first.
3 problemsA 23 cm and a 19 cm strip joined. How long in all?
Answer 42
Why 23 + 19 = 42 centimetres.
Can you add 8 centimetres to 3 metres straight away?
Answer No. The units are different.
Why Lengths only add when they are in the same unit.
28 cm and 34 cm joined. How long in all?
Answer 62
Why Tens with tens first.
Build It Up
The same ideas with more to keep track of.
1 problemA 50 cm rope loses 16 cm. How long now?
Answer 34
Why 50 − 16.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
3 problemsA 40 cm and a 25 cm stick. How much longer is the first?
Answer 15
Why 40 − 25.
The Ribbon Roll: A ribbon is 35 cm long. Leo cuts off 12 cm. How long is the ribbon now?
Answer 23 cm
Why 35 − 12 = 23 centimetres.
Two Jumps: Ana jumped 46 cm, then 27 cm further. How far did she jump in all?
Answer 73 cm
Why 46 + 27 = 73 centimetres.