Grade 2 · Math · Unit

Story Problems Within 100

4 lessonsabout 2 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 4 of 9 in the Grade 2 Math Scope and Sequence

What's included in this unit

4 lessons in teaching order, each with its objective and a teacher note
16 practice pages to print, with an easier and a harder page where available
2 classroom tools for the projector
4 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

One-step stories with a bar model

Children solve one-step story problems within 100 in which the end, the change, or a part is missing, with a bar model and an equation, and write the question for a story that has none.

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

2 class days

Day 1Teach: The Missing Question · 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 Missing Question on the projector.

Practice on paper

Story Problems Within 100: Bar Model
Core page Easier page Harder page
Story Problems Within 100: Question, Equation, Answer
Core page Easier page Harder page

Check-up page

One more page of Story Problems Within 100: Bar Model to collect at the end of the lesson.

Teacher note

Common mistakes: With two-digit numbers children stop reading and just compute: they add the two numbers in every story. When more are added and the story asks for the change (34 + ? = 52), they write 34 + 52.
Words to use: Open The Missing Question and tell a story with no numbers, for example: "There are some pencils in a box. Sam puts in some more." Ask: "What could we ask?" Collect their questions, then tell the numbers one at a time. Draw the bar: "Which number is all of them? Which part do we know? Where is the question mark?" Write 34 + ? = 52 first, then the equation you solve, 52 − 34 = 18.
What to watch for: On the bar-model page one story asks for the end and two ask for the change; its easier page asks for the end in all three stories and the first is worked; its harder page asks for the change or for a missing part. The second page, Question, Equation, Answer, has three more stories and no bar. On the page for everyone one question is missing and the child writes it: accept any question that needs both numbers ("How many are still on the table?"). One story there compares two boxes. Either true equation counts.

Lesson 2

What was there at the start?

Children solve one-step story problems within 100 in which the starting amount is unknown, with a bar model and an equation.

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

2 class days

Day 1Teach: The Missing Question · 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 Missing Question on the projector.

Practice on paper

Find the Start: Story Problems Within 100
Core page Easier page Harder page

Check-up page

One more page of Find the Start: Story Problems Within 100 to collect at the end of the lesson.

Teacher note

Common mistakes: Children do what the story says: when 17 more are put in, they add 17 to the number they see, and when some are taken out, they subtract. In these stories the words point the wrong way: "takes out 25, now there are 38 left" calls for adding.
Words to use: Open The Missing Question and choose "one thing happened". Tell a story with no numbers: "There are some pencils in a box. Sam puts in some more. Now there are a lot." Ask, "What could we ask?" until someone asks what was there at the start (ask it yourself if no one does); choose that place as the one to work out and give the other two numbers (the tool goes up to twenty). Then draw the bar model with two-digit numbers: "45 are in the box now. 17 were put in. The question mark is what was there before." Write ? + 17 = 45, then 45 − 17 = 28.
What to watch for: On the page for everyone all three stories ask for the start. When some were added, the end is the whole (? + 17 = 45). When some were taken away, the start is the whole, so the question mark goes in the long bar and the child adds (? − 25 = 38, so 38 + 25 = 63). On the easier page every number is a multiple of 10 and the first story is worked. On the harder page one story asks for the change, so the child has to read which number is missing. Accept either equation: ? + 17 = 45 or 45 − 17 = 28.

Lesson 3

Compare stories: more and fewer

Children solve compare stories within 100 in which the difference, the larger amount, or the smaller amount is unknown, with two bars and an equation.

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

2 class days

Day 1Teach: The Planks · 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 Planks on the projector.

Practice on paper

Compare Stories Within 100: Two Bars
Core page Easier page Harder page

Check-up page

One more page of Compare Stories Within 100: Two Bars to collect at the end of the lesson.

Teacher note

Common mistakes: Children add when they read "more" and subtract when they read "fewer" without asking which box has more. That fails when the story says "That is 29 more than in the blue box": the red box has more, so the blue box has fewer, and the child has to subtract.
Words to use: Open The Planks and drag the two planks to 15 and 9: "The red box has 15. The blue box has 9. Which box has more? How many more?" Carry away the piece that sticks out and say all three sentences: "The red box has 6 more. The blue box has 6 fewer. 9 and 6 more make 15." Then draw two bars on the board: "There are 85 oranges in a red box. That is 29 more than in the blue box. Which bar is longer?" The dashed piece is the piece that sticks out, drawn next to the short bar. Write 85 in the long bar, 29 in the dashed piece, a question mark in the short bar, and 85 − 29 = 56: "The blue box has 56."
What to watch for: On the page for everyone, the bars are drawn: the longer bar is the box with more, and the dashed piece next to the shorter bar is the difference. In all three stories, "more" means add and "fewer" means subtract, so a correct page does not yet show that the child compared. On the easier page, every number is a multiple of 10 and the first story is done. On the harder page, two stories say "That is … more than" or "That is … fewer than," and the child draws the bars next to the red and blue squares. Ask "Which box has more?" before any number is written.

Lesson 4

Two-step stories

Children solve story problems within 100 that need two steps of adding or subtracting, and write an equation for each step.

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

2 class days

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

Practice on paper

Two-Step Story Problems Within 100
Core page Easier page Harder page
Two-Step Word Problems
Core page

Check-up page

One more page of Two-Step Story Problems Within 100 to collect at the end of the lesson.

Teacher note

Common mistakes: Children do one step and stop, or they add all three numbers no matter what happens in the story. Many start the second step from the first number of the story again instead of from the answer to the first step.
Words to use: Tell a story in two parts and stop in the middle: "There are 36 apples in a box. Mia takes out 21." Ask, "How many are in the box now?" Write 36 − 21 = 15 and circle the 15. "Then Mia puts in 27. Which number do we start from now?" Write 15 + 27 = 42 under it and draw an arrow from the 15 to the start of the second line. Have a child retell the whole story with the numbers.
What to watch for: On the page for everyone, the two steps are printed as a) and b) with boxes: the answer to step a) is written again at the start of step b). The easier page has two stories with multiples of 10. On the harder page, only the answer box is printed, and the child works out the two steps in the dotted space. Where two children take some, adding the two amounts first and subtracting once is right, too. The second page, Two-Step Word Problems, has three stories within 20 with the steps printed: start there with children who are not sure. A child who adds all three numbers needs to act the story out with counters and small numbers.

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, One-step stories with a bar model (1 task)
Part 2: Lesson 2, What was there at the start? (1 task)
Part 3: Lesson 3, Compare stories: more and fewer (1 task)
Part 4: Lesson 4, Two-step stories (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