Idea 19of 24Builds onSame bottom number: compare the tops
Add fractions with the same bottom number
What is 3/8 + 2/8?
Today you'll discover
- why same-size parts just count
- why the bottom number stays
- how to add in a story
Think first3/8 m of red ribbon and 2/8 m of blue
What is 3/8 + 2/8?
Decide first, then press Next. Check that the parts are the same size.
A red ribbon bar with three of eight parts shaded and a blue bar with two of eight. The parts are counted, then slide together into a bottom bar of five eighths, then 3/8 + 2/8 = 5/8 is written. The last step shows a garden: four tenths carrots, three tenths beans.
See the whole ideathe big idea and the key word, in one place
The big idea
To add fractions with like denominators, add the numerators and keep the denominator.
Easy to get wrongNever add the bottom numbers. 3/8 + 2/8 is not 5/16: that would be less than 3/8 alone.
In a storyA pizza in 8 slices: you eat 3/8 and a friend eats 2/8. Together you eat 5/8, and 3/8 is left.
Key word
- like denominators
- denominators that are the same, like the 8s in 3/8 and 2/8
Ready to use it?
- Add fractions with like denominators.
- Solve a story problem by adding fractions.