Cogito
Grade 5 Math · Chapter 1 · Lesson 4
Comparing Decimals to Thousandths
Biggest place first, every time.
10 problems · about 15 minutes · 5.NBT.A.3
What this lesson teaches
The child compares and orders decimals to thousandths and justifies the order.
- Write both decimals to the same number of places.
- Compare from the biggest place, moving right.
- The first place where they differ decides.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
2 problemsReview — Thousandths: In 0.914, what digit is in the thousandths place?
Answer 4
Why The 4.
Review — Powers of Ten: What is 7 × 10² ?
Answer 700
Why 700.
Warm Up
Straightforward practice. Get the method working first.
4 problemsWhich is bigger, 0.608 or 0.61?
Answer 0.61.
Why 0.610 beats 0.608.
Does a decimal with more digits have to be bigger?
Answer No.
Why The places decide, not the number of digits.
Which is bigger, 0.5 or 0.462?
Answer 0.5.
Why Compare the tenths.
Which is bigger, 0.207 or 0.27?
Answer 0.27.
Why 0.27 is 0.270.
Build It Up
The same ideas with more to keep track of.
2 problemsWhich is bigger, 0.9 or 0.1234?
Answer 0.9.
Why More digits is not more.
Which place do you compare first?
Answer The biggest one.
Why Left to right.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
2 problemsThe Times: Which is faster, a time of 9.85 seconds or 9.9 seconds?
Answer 9.85 seconds.
Why 9.85 is less than 9.90.
The Weights: Which is heavier, 2.305 kg or 2.35 kg?
Answer 2.35 kg.
Why 2.350 beats 2.305 at the hundredths place.