Cogito
Grade 3 Math · Chapter 6 · Lesson 4
Measuring to Halves and Fourths
A ruler has marks between the numbers.
10 problems · about 13 minutes · 3.MD.B.4
What this lesson teaches
The child measures lengths to the nearest half or fourth of a unit.
- Rulers have marks between the whole numbers.
- Halves and fourths let you name a length in between.
- This is what fractions are for.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
3 problemsReview — Two-Step Graph Problems: Bars of 40, 15 and 5. How many more is the first than the other two together?
Answer 20
Why 40 − 20 = 20.
Review — Scaled Bar Graphs: A scale of 5, bar at the seventh mark. What value?
Answer 35
Why The bar shows 35.
Review — Scaled Picture Graphs: Each picture is 5. A column has 8 pictures. How many?
Answer 40
Why The column stands for 40.
Warm Up
Straightforward practice. Get the method working first.
3 problemsHow many fourths make three quarters?
Answer 3
Why Three fourths is three of the small marks.
Why does a ruler have marks between the numbers?
Answer Real lengths land between whole numbers.
Why The small marks let you name a length that falls in between.
How many fourths make one half?
Answer 2
Why Half of 4.
Build It Up
The same ideas with more to keep track of.
1 problemHow many fourths are in one whole inch?
Answer 4
Why All of them.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
3 problemsHow many fourths are in 2 whole inches?
Answer 8
Why 4 twice.
Between Marks: An object ends halfway between 5 and 6 inches. How many fourths past the 5 is that?
Answer 2 fourths
Why 2/4 is the same as one half.
Quarter Past: An object ends one fourth past the 4 inch mark. How many fourths past 4?
Answer 1 fourth
Why It is 4 and one fourth inches.