Grade 1 · Math · Unit

Story Problems Within 20

5 lessonsabout 3 weeks

The unit ends with three more days: a review day, the unit check, and a day to act on what the check showed.

Unit 3 of 8 in the Grade 1 Math Scope and Sequence

What's included in this unit

5 lessons in teaching order, each with its objective and a teacher note
21 practice pages to print, with an easier and a harder page where available
4 classroom tools for the projector
3 activities and pages that children do on a screen
5 check-up pages to collect

The whole unit in one file

Print every page of the unit at once, with the teacher guide first. The guide has one page per lesson: the objective, what to hand out, and the teacher note.

Teacher guide only (PDF)

The unit file, the teacher guide, and saved pages are included with the Teacher plan.

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Lessons

Lesson 1

Word problems within 10

Children solve addition and subtraction story problems within 10 and say or write the equation that tells the story.

StandardCommon Core 1.OA.A.1Operations and Algebraic Thinking

3 class days

Day 1Teach: The Missing Question · Practice on paper (Core page)
Day 2Practice and check: Practice on paper (Easier page, Harder page) · Practice on screen · Check-up page
Day 3Reteach and extend: Act on the check-up pages: reteach the children who are not there yet, with the tool and a new page from the maker; the others take a harder page.

Lesson 2

Find the missing part

Children solve put-together stories within 20 in which the total and one part are known: they mark the missing part with a question mark in a bar model and write an equation for the story.

StandardCommon Core 1.OA.A.1Operations and Algebraic Thinking

2 class days

Day 1Teach: Number Bonds Board · Practice on paper (Core page)
Day 2Practice and check: Practice on paper (Easier page, Harder page) · Check-up page

Warm up and teach

Open Number Bonds Board on the projector.

Practice on paper

Find the Missing Part: Story Problems
Core page Easier page Harder page

Check-up page

One more page of Find the Missing Part: Story Problems to collect at the end of the lesson.

Teacher note

Common mistakes: Children add the two numbers they see (12 in all and 7 in the red box become 19), because nothing is taken away in the story. Others write the total in one of the small parts of the bar.
Words to use: Open the Number Bonds Board, set the number to 10, tap counters across until the left part holds 6, and put the cloth over the right part: "Two boxes have 10 apples in all. 6 are in the red box. What do we know? What are we looking for?" Draw the bar on the board: "The long bar is all 10. The two short bars are the parts. One part is 6. The other part is our question mark." Write 6 + ? = 10, then take the cloth off.
What to watch for: On the page for everyone the total is between 11 and 20. The easier page stays within 10 and its first story is worked, so a child sees what goes where; the harder page uses whole tens (70 in all, 30 in the red box). Check the bar first: the total belongs in the long bar. For 12 in all and 7 in one part, the key writes 7 + 5 = 12; 12 − 7 = 5 is just as correct. A child who answers 19 has added: build the 12 with counters and cover the 7.

Lesson 3

What happened in the middle?

Children solve stories within 20 in which the start and the end are known and the change is missing (some came or some left): they mark the change with a question mark in a bar model and write an equation for the story.

StandardCommon Core 1.OA.A.1Operations and Algebraic Thinking

2 class days

Day 1Teach: The Gap · Practice on paper (Core page)
Day 2Practice and check: Practice on paper (Easier page, Harder page) · Check-up page

Warm up and teach

Open The Gap on the projector.

Practice on paper

What Happened in the Middle? Story Problems
Core page Easier page Harder page

Check-up page

One more page of What Happened in the Middle? Story Problems to collect at the end of the lesson.

Teacher note

Common mistakes: Children add the two numbers in the story no matter what happened. In a story where some leave, many write the starting number in a small part of the bar, but in those stories the start is the whole.
Words to use: Open The Gap and choose "up to sixteen" in its settings. Count the marks on the ground together (say there are 8), tap "Show the gap," and count again (say 13). Write both numbers: "Did some come or did some leave? How many?" Take a child's number and try it. Then draw the bar: "More came, so 13 is all of them. 8 were there at the start. The question mark is what came." Write 8 + ? = 13. When some left, the first count is all of them.
What to watch for: The page for everyone has one story in which some more come and two in which some leave, with a larger number from 11 to 20. The easier page stays within 10 and its first story is worked; the harder page uses whole tens. Ask "Which number is all of them?" before the child writes: in 8 + ? = 13 it is the end, in 12 − ? = 7 it is the start. Either true equation counts (13 − 8 = 5 for 8 + ? = 13).

Lesson 4

How many more? How many fewer?

Children compare two amounts within 20 in a story, shown as two lined-up rows of pictures, and find how many more or how many fewer.

StandardCommon Core 1.OA.A.1Operations and Algebraic Thinking

3 class days

Day 1Teach: The Planks · Practice on paper (Core page)
Day 2Practice and check: Practice on paper (Easier page, Harder page) · Practice on screen · Check-up page
Day 3Reteach and extend: Act on the check-up pages: reteach the children who are not there yet, with the tool and a new page from the maker; the others take a harder page.

Warm up and teach

Open The Planks on the projector.

Practice on paper

Compare Word Problems
Core page Easier page Harder page

Practice on screen

Vet's Diagnosis Window — Word-Problem Modeling

Check-up page

One more page of Compare Word Problems to collect at the end of the lesson.

Make more

Make more pages like this with the Word Problems maker.

Teacher note

Common mistakes: Children hear "more" and add the two amounts (12 and 7 become 19), or they answer with the larger amount. "How many fewer" is harder than "how many more", although it is the same difference.
Words to use: Open The Planks and drag the two planks to 12 and 7 before you say anything: "Mia has 12 stickers. Ben has 7. Where do you see how many more?" Let the class say how long the piece under the bracket is, then move it to the end of the short plank: "Mia has 5 more than Ben. Ben has 5 fewer than Mia. Ben needs 5 more to have as many as Mia." Say all three sentences for every pair.
What to watch for: The page shows the two amounts as two rows of pictures that start at the same line. Have the child circle the pictures that stick out before writing the number in the box; the dotted space is for a drawing or an equation. On the page for everyone the larger amount is 11 to 14 in both stories; the easier page stays within 10; the harder page has three stories. A child who writes 19 has added: cover what both rows have and ask what is left. Children can also practice story problems on screen.

Lesson 5

Stories with three numbers

Children solve story problems that add three numbers with a total up to 20, with a drawing and an equation, and look for two numbers that make ten before they add.

StandardCommon Core 1.OA.A.2Operations and Algebraic Thinking

2 class days

Day 1Teach: Practice on paper (Core page)
Day 2Practice and check: Practice on paper (Easier page, Harder page) · Practice on screen · Check-up page

Practice on paper

Stories with Three Numbers
Core page Easier page Harder page
Add Three Numbers
Core page Easier page Harder page

Practice on screen

Add Three Numbers — Three-Part Number Bond

Check-up page

One more page of Stories with Three Numbers to collect at the end of the lesson.

Teacher note

Common mistakes: Children add the first two numbers and stop, or they count all three groups by ones and lose count. Few look at all three numbers before they start, so a pair that makes ten goes unused.
Words to use: Write a story on the board: "There are 4 pencils on the table, 7 in a box, and 6 in a basket. How many pencils are there in all?" Draw three groups of dots and write 4 + 7 + 6. Ask: "Which two numbers make ten?" Circle 4 and 6 and write 10 + 7 = 17. Then point to the groups in another order: "Did the total change?" Any order gives the same total, so we can start with the ten.
What to watch for: On the page for everyone every story has two numbers that make ten, in a different place each time: the child draws the three groups in the box, writes the three numbers in the frame, and adds. The easier page has totals from 6 to 10 and no ten to find. On the harder page one story has a ten, one has a double (such as 3 + 8 + 3), and one has neither, so the child has to look first. The second page, Add Three Numbers, has twelve problems with no story. On its page for everyone each has a pair that makes ten; on its harder page only half do. A child who adds from left to right and is correct has done nothing wrong: ask, "Is there a faster way?"

Unit check: before and after

Two short paper checks made from this unit's own worksheets. Give Check A before you teach the unit and Check B after it, and you can see what changed. Each part belongs to one lesson.

Part 1: Lesson 1, Word problems within 10 (1 task)
Part 2: Lesson 2, Find the missing part (1 task)
Part 3: Lesson 3, What happened in the middle? (1 task)
Part 4: Lesson 4, How many more? How many fewer? (1 task)
Part 5: Lesson 5, Stories with three numbers (1 task)

Check A (PDF) · 2 pages Check B (PDF) · 2 pages

Printing a check counts as a download, like any worksheet.

Answer key A Answer key B Teacher pages: points, class record, and what to do next

The answer keys and the teacher pages come with the paid Teacher plan.

This is a classroom check of this unit's lessons. It is not a standardized test, and its points are not a grade.

Unit checks