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Skills Covered

Solve change unknown stories within 100: how many came?
Solve change unknown stories: how many went away?
Count up on an open number line to find a missing part

Solve start unknown stories: what was there at first?
Write a number sentence with a missing number
Use a number bond or a bar model to find the unknown

How to Use This Pack

Five pages of story problems where the number to find is not the one at the end. Page 1 asks how many more came (Leo has 28 toy cars, now he has 63: how many did he get?) and page 2 how many went away; students count up on an open number line, and the key counts up to the next ten, then the tens, then the ones. Page 3 asks what was there at the start, with a number bond: the whole goes on top. Page 4 mixes all four kinds, and students write the number sentence with the missing number in its place (28 + __ = 63). Page 5 fills in a bar model for each story. Every page starts with a worked example.

In the Classroom

Act out the example on page 3 with cubes hidden in a cup: "Sam had some blocks. He got 25 more. Now he has 61." Ask what we know (the part he got and the whole) and what we do not (the start). Write it as __ + 25 = 61 and talk about why subtracting 61 − 25 finds the missing part.

At Home

Hide some coins under a cup, add a few more on top, and tell your child how many there are in all. Ask how many were under the cup to start, then lift it to check.

Tips for Success

Ask what you know and what you need to find before you solve
Count up from the smaller number to the bigger one: the jumps are the missing part
The whole goes at the top of a number bond, the parts below
Put your answer back into the story to check it

Common Core Standards Alignment

This pack supports the following Common Core State Standards for Mathematics:

1.OA.D.8 Solve for the missing number in adding or subtracting equations like 9 + ? = 15 or ? - 4 = 6.
2.OA.A.1 Solve one- and two-step story problems with sums and differences up to 100, with the unknown in any position, using drawings and equations.
2.NBT.B.5 Add and subtract to 100 fluently with place-value strategies, properties of addition, or the link between adding and subtracting.
2.MD.B.6 Show whole numbers as distances from 0 on an evenly marked number line, and show sums and differences up to 100 as jumps on it.

Missing Number Word Problems Within 100

2nd Grade

A 5-page pack of 2nd grade word problems with the change or the start unknown, using two-digit numbers within 100. Count up on an open number line to find how many more came or how many went away, use a number bond to find what was there at the start, write a number sentence with the missing number, and fill in bar models. Every page comes in color and in black and white. Answer keys included.

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What’s Included

5 worksheets in color and in black and white, with answer keys (15 pages)
16 story problems and 5 worked examples, numbers within 100
Open number lines, number bonds and bar models
Change unknown and start unknown stories, adding and taking away

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