Sometimes the whole is missing. Sometimes a part is missing.
Step 1: Let's Learn
Read it, or press Listen and follow the words.
Missing whole
If you know both parts, put them together.
Missing part
If you know the whole and one part, take that part away.
Draw the diagram first. Then you can see which one it is.
Find out what is missing first
Missing whole means add. Missing part means subtract or count up. That decision is the whole problem.
Key words can mislead
"Altogether" usually means add, and not always. Read the situation, not just the vocabulary.
Step 2: Try It Yourself
Tap and try it out.
On the top shelf and On the bottom shelf
20
10
Books in all
30
20 and 10 make 30.
Step 3: Watch an Example
One step at a time.
Watch Ana Find a Part
There are 30 books in all. 20 are on the top shelf.
- Step 1
She draws the whole bar and labels it 30.
Step 4: Your Turn
Practice makes it stick.
At the Library
Problem 1 of 2
25 books in all. 15 are red. How many are not red?
Red and Not red
15
?
In all
25
Red
Not red
books
On the Bus
Problem 2 of 2
14 children get on. Then 12 more. How many in all?
children
Which Piece Is Missing?
1 of 3
Whole 30, one part 10. Other part?
2 of 3
Parts 16 and 13. What is the whole?
3 of 3
Whole 28, one part 8. Other part?
Step 5: Quick Check
Show what you know.
Question 1 of 2
Whole 35, one part 15. Other part?
Question 2 of 2
You know both parts. What do you do?
What You Learned
- Some stories hide the whole. Add the parts.
- Some stories hide a part. Take the known part away.
- The diagram tells you which one it is.