Cogito
Grade 2 Math · Chapter 4 · Lesson 10
Two-Step Word Problems Within 100
Find the hidden question first.
10 problems · about 15 minutes · 2.OA.A.1
What this lesson teaches
The child solves two-step word problems within 100, tracking the intermediate answer.
- Some problems hide a first question.
- Answer it, write it down, then finish.
- Check the answer makes sense before stopping.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
3 problemsReview — Word Problems Within 100: 47 birds. 28 fly away. How many are left?
Answer 19
Why 47 − 28 = 19.
Review — Checking by Adding: 75 − 38 = ?
Answer 37
Why 75 − 38 = 37, and 37 + 38 = 75.
Review — Subtracting With a Broken Ten: 45 − 28 = ?
Answer 17
Why 45 − 28 = 17.
Warm Up
Straightforward practice. Get the method working first.
3 problems55 apples. 27 more arrive. 34 are sold. How many are left?
Answer 48
Why 55 + 27 = 82, and 82 − 34 = 48.
What should you do with the middle answer?
Answer Write it down and use it in step two.
Why The middle answer feeds the second step.
40 sweets. 25 more. 32 eaten. How many now?
Answer 33
Why 40 + 25 = 65 first.
Build It Up
The same ideas with more to keep track of.
1 problem86 marbles. 39 lost. 15 found. How many now?
Answer 62
Why 86 − 39 = 47 first.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
3 problems28 red and 34 blue pens. 19 given away. How many left?
Answer 43
Why 28 + 34 = 62 first.
The Library: A shelf had 52 books. 19 were borrowed. Then 27 were returned. How many now?
Answer 60 books
Why 52 − 19 = 33, and 33 + 27 = 60.
The Bus: 34 people were on a bus. 18 got on, then 25 got off. How many are on now?
Answer 27 people
Why 34 + 18 = 52, and 52 − 25 = 27.