Cogito
Grade 3 Math · Chapter 5 · Lesson 4
Fractions on the Number Line
A fraction is a number, so it has a place.
10 problems · about 14 minutes · 3.NF.A.2
What this lesson teaches
The child locates a fraction on a number line by partitioning the unit interval.
- A fraction is a number with a place on the line.
- Cut the space from 0 to 1 into equal parts.
- Count the parts from 0.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
3 problemsReview — Fractions as Copies of a Unit: How many copies of 1/8 make 5/8?
Answer 5
Why 5/8 is five copies of 1/8.
Review — Unit Fractions: Which is bigger, 1/4 or 1/6?
Answer 1/4
Why 1/4 is bigger, even though 4 is the smaller number.
Review — Equal Parts of a Whole: A shape cut into 5 equal parts. What is the denominator?
Answer 5
Why The denominator is 5.
Warm Up
Straightforward practice. Get the method working first.
3 problemsA line cut into 5 parts. How many parts along is 2/5?
Answer 2
Why 2/5 is two parts along from 0.
Where do you start counting on the line?
Answer At 0.
Why Every number on a line is measured from 0.
A line cut into 4 parts. How many parts along is 3/4?
Answer 3
Why The numerator.
Build It Up
The same ideas with more to keep track of.
1 problemHow many equal parts do you cut for eighths?
Answer 8
Why The denominator.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
3 problemsMust the marks be evenly spaced?
Answer Yes. Otherwise the parts are not equal.
Why A fraction needs equal parts.
Reading the Line: A line from 0 to 1 is cut into 6 parts. A dot sits on the fifth mark. What fraction is it?
Answer 5 sixths
Why It is 5/6.
Halfway: On a line cut into 8 parts, which mark is halfway between 0 and 1?
Answer 4 eighths
Why 4/8 sits halfway.