Cogito
Grade 4 Math · Chapter 6 · Lesson 4
Comparing Decimals
Same unit first, then compare.
10 problems · about 14 minutes · 4.NF.C.7
What this lesson teaches
The child compares two decimals to hundredths and justifies the comparison.
- Write both decimals to the same number of places.
- Compare from the left, biggest place first.
- Length of the writing never decides size.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
2 problemsReview — Why 0.7 and 0.70 Are Equal: 0.2 in hundredths. How many?
Answer 20
Why 0.2 = 0.20 = 20/100.
Review — Hundredths: How many hundredths are in 0.09?
Answer 9
Why 0.09 is 9/100.
Warm Up
Straightforward practice. Get the method working first.
4 problemsWhich is bigger, 0.9 or 0.89?
Answer 0.9.
Why 90 hundredths beats 89 hundredths.
Which place do you compare first?
Answer The tenths.
Why Tenths are worth more than hundredths, so they decide first.
Which is bigger, 0.7 or 0.68?
Answer 0.7.
Why 0.7 is 0.70.
Which is bigger, 0.45 or 0.54?
Answer 0.54.
Why Compare the tenths first.
Build It Up
The same ideas with more to keep track of.
2 problemsWhich is bigger, 0.3 or 0.03?
Answer 0.3.
Why 30 hundredths against 3.
0.25 in hundredths. How many?
Answer 25
Why Twenty-five hundredths.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
2 problemsThe Jumps: Ana jumped 1.35 metres and Leo 1.4. Who jumped further?
Answer Leo.
Why 1.40 beats 1.35.
The Weights: Which is heavier, 0.6 kg or 0.55 kg?
Answer 0.6 kg.
Why 60 hundredths beats 55 hundredths.