Cogito
Grade 5 Math · Chapter 8 · Lesson 6
Converting Units in Problems
Get everything into one unit first.
10 problems · about 15 minutes · 5.MD.A.1
What this lesson teaches
The child converts among units in one system and uses conversions in multistep problems.
- Convert everything to one unit before calculating.
- To a smaller unit, multiply. To a bigger one, divide.
- Only matching units can be added.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
2 problemsReview — The Shape Hierarchy: Is every rectangle a parallelogram?
Answer Yes.
Why A rectangle sits inside the parallelogram group.
Review — Patterns as Pairs: A adds 3, B adds 12, from 0. What is B when A is 9?
Answer 36
Why 36.
Warm Up
Straightforward practice. Get the method working first.
4 problems1.25 litres in millilitres?
Answer 1250
Why 1,250 millilitres.
What must you do before adding amounts in different units?
Answer Convert them to one unit.
Why Only matching units can be added.
3.5 metres in centimetres?
Answer 350
Why 3.5 × 100.
2,500 grams in kilograms?
Answer 2.5
Why 2,500 ÷ 1,000.
Build It Up
The same ideas with more to keep track of.
2 problems0.75 litres in millilitres?
Answer 750
Why 0.75 × 1,000.
Going to a bigger unit, does the number get smaller?
Answer Yes. Fewer of them are needed.
Why Metres against centimetres.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
2 problemsThe Two Jugs: 1.5 litres plus 750 ml. How many millilitres in all?
Answer 2250 ml
Why 2,250 millilitres.
The Rope: 2.4 metres plus 60 cm. How many centimetres in all?
Answer 300 cm
Why 300 centimetres, which is 3 metres.