A fraction only makes sense if the parts are equal.
Step 1: Let's Learn
Read it, or press Listen and follow the words.
The bottom number counts the parts the whole was cut into.
Denominator is the bottom number. It tells how many equal parts the whole was cut into.
More parts, smaller pieces
Cut a cake into 8 instead of 4 and every piece gets smaller.
Unequal parts are not fractions
Two pieces of different sizes are not halves, however you draw them.
Fractions require equal parts
A shape cut into 4 pieces only shows fourths if all four pieces are the same size. Cut a circle into one huge piece and three slivers and you have four pieces, but no fourths. Every fraction question begins with checking that the parts are genuinely equal.
Equal in amount, not in shape
Two halves of a square can be two rectangles or two triangles. They look different but cover the same amount of surface, so both are halves. Equal means equal in area, which is why the area chapter comes just before this one.
The number of parts names the fraction
Two equal parts give halves, three give thirds, four give fourths, eight give eighths. The number of parts you cut the whole into becomes the bottom number of the fraction, and it is what gives each piece its name.
Step 2: Try It Yourself
Change the number of parts and watch each piece shrink.
The whole is cut into 4 equal shares, called fourths.
0/4 shaded
These pieces are not the same size, so they are not equal shares.
How many pieces
Step 3: Watch an Example
One step at a time.
Watch Ana Check a Cut
Ana is shown a circle cut into 4 pieces of different sizes.
- Step 1
She counts the pieces: 4.
Step 4: Your Turn
Practice makes it stick.
The Pizza
Problem 1 of 2
A pizza is cut into 6 equal slices. What is the denominator?
Smaller Pieces
Problem 2 of 2
Which gives smaller pieces, cutting into 4 parts or into 8?
Equal Parts
1 of 3
A shape cut into 8 equal parts. What is the denominator?
2 of 3
Must the parts be equal to name a fraction?
3 of 3
A whole cut into 3 equal parts. What is one part called?
Step 5: Quick Check
Show what you know.
Question 1 of 2
A shape cut into 5 equal parts. What is the denominator?
Question 2 of 2
What does the denominator tell you?
What You Learned
- A fraction needs equal parts.
- The denominator counts those parts.
- More parts always means smaller pieces.