Cogito
Grade 6 Math · Chapter 2 · Lesson 6
Converting Units with Rates
Changing the unit without changing the amount.
10 problems · about 18 minutes · 6.RP.A.3
What this lesson teaches
The child converts between units by multiplying or dividing by a conversion rate.
- A unit conversion is a rate like any other.
- Going to a smaller unit multiplies; going to a bigger unit divides.
- The amount stays the same — only the unit changes.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
3 problemsReview — Finding the Whole from a Percent: 25% of a number is 11. What is the number?
Answer 44
Why 44.
Review — Comparing with Unit Rates: 6 cakes for £9. Price for one, in pounds?
Answer 1.5
Why £1.50 each.
Review — Finding a Percent of a Number: What is 30% of 90?
Answer 27
Why 3 × 9 = 27.
Warm Up
Straightforward practice. Get the method working first.
3 problems5 km in metres?
Answer 5000
Why 5000 m.
4 km in metres?
Answer 4000
Why × 1000.
250 cm in metres? (100 cm in a metre.)
Answer 2.5
Why ÷ 100.
Build It Up
The same ideas with more to keep track of.
2 problems2 hours in minutes?
Answer 120
Why × 60.
180 minutes in hours?
Answer 3
Why ÷ 60.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
2 problemsThe Bottle: 2 litres is how many millilitres? (1 litre is 1000 ml.)
Answer 2000
Why 2000 ml.
The Bag: 3500 g is how many kilograms? (1 kg is 1000 g.)
Answer 3.5
Why 3.5 kg.