Lesson 5.5 · Subtraction
Add or subtract?
You can add and you can subtract. But how do you know which one a story needs? Listen for clues!
Joining or taking away?
Some stories put groups together. Things come, join or get added. Then you add, and you get more.
Some stories take things away. Things leave, get eaten or get used. Then you subtract, and you get fewer.
Add or subtract?
- More things come or join: add with .
- Things go away: subtract with .
Worked example: More come
There are 3 dogs at the park. 2 more dogs come. How many dogs are at the park now?
More dogs come, so add. . There are 5 dogs.
Worked example: Some leave
There are 6 dogs at the park. 2 dogs go home. How many dogs are at the park now?
Dogs go away, so subtract. . There are 4 dogs.
Worked example: Check the answer
Ben has 4 shells. He finds 3 more. Is the answer more than 4 or less than 4?
He finds more, so he will have more than 4. Add: . Ben has 7 shells.
Tip
Check your answer. If things came, your answer should be bigger than the start. If things went away, it should be smaller.
Practice
There are 2 ducks in a pond. 3 more ducks swim over. Do you add or subtract?
Kim has 5 grapes. She eats 2. Do you add or subtract?
There are 2 ducks in a pond. 3 more ducks swim over. How many ducks are in the pond now?
Type a number.
Kim has 5 grapes. She eats 2. How many grapes are left?
Type a number.
There are 6 kids on the slide. 2 more kids come. How many kids are there now?
Type a number.
There are 9 balloons. 5 float away. How many balloons are left?
Type a number.
Nora has 7 beads. She gets 3 more. How many beads does she have now?