A fraction is a number that names part of a whole. The bottom number tells how many equal parts the whole is cut into. The top number tells how many of those parts you have. If a pizza has eight equal slices and you eat three, you ate three eighths.
Peabody: Hi, I am Peabody! Here is one whole pancake. A fraction tells us about a part of it. It starts with a whole.
Crumb: I am Crumb! I will cut my cake in four pieces. Careful, the pieces must be equal. Equal means the same size. Unfair pieces are not fractions.
Peabody: The bottom number is the denominator. It says how many equal parts make the whole. Four equal pieces means the bottom number is four.
Crumb: I ate one piece! The top number is the numerator. It counts the pieces we are talking about. One of four pieces is one fourth.
Peabody: If Crumb eats two pieces, that is two fourths. If we eat all four, that is four fourths. Four fourths is the whole cake.
Crumb: Here is a surprise. If I cut the cake in eight pieces, each piece is smaller. A bigger bottom number means smaller pieces. One eighth is less than one fourth.
Crumb: Here is a recap! A fraction names equal parts of a whole. The bottom number counts all the parts. The top number counts the parts you have. Now go and share something fairly!
Quiz: five questions
Tap an answer. Stuck? Tap the hint. Nothing is scored or saved.
Question 1 of 5
What does the bottom number of a fraction tell you?
The words
fraction
a number that names part of a whole
numerator
the top number: how many parts you have
denominator
the bottom number: how many equal parts in the whole
equal
exactly the same size or amount
whole
all of something, not cut up
Make it: put the explainer in order
Tap the scenes in the order they happen. Which comes first?
Try it without a screen: Fold a fraction
You need: 3 paper strips the same length, crayons.
Leave strip one whole and color it all.
Fold strip two in half. Open it and color one half.
Fold strip three in four equal parts. Color three parts.
Line them up. Which colored part is longest? Write the fraction on each strip.
For the grown-up
This explainer introduces unit fractions and fractions of a whole with equal parts (about grades 2 to 3 in the Common Core). The two ideas to listen for: the parts must be equal, and a bigger bottom number means smaller pieces. Use food and paper to show it. Common slip: comparing only the bottom numbers and thinking one eighth is more than one half. Nothing here is saved or shown to anyone.