Missing Number Equations Within 20

2nd Grade MathAddition and Subtraction5 pages

About this worksheet

Printed as Addition and Subtraction Adventure, this 2nd grade math worksheet runs from fact fluency to a two-step story in four parts. Students answer twelve facts such as 8 + 6 and 17 - 8, find unknowns in equations like 7 + ___ = 15, then write their own equations for Maya's sticker problem (28 grow to 45) and the crayon comparison where Jenna has 19 fewer than Caleb's 36. A final challenge follows Liam picking 34 and then 25 apples before 18 are baked into pies. The page pairs Common Core 2.OA.1 story work with 2.OA.2 fluency, and the key writes out the think-addition reasoning for every missing number.

Remix for free

$Missing Number Equations Within 20: Addition and Subtraction - page 1$

$Missing Number Equations Within 20: Addition and Subtraction - page 2$

$Missing Number Equations Within 20: Addition and Subtraction - page 3$

$Missing Number Equations Within 20: Addition and Subtraction - page 4$

$Missing Number Equations Within 20: Addition and Subtraction - page 5$

Curriculum objectives covered

2.OA.1

“Use addition and subtraction within 100 to solve one- and two-step word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using drawings and equations with a symbol for the unknown number to represent the problem.”

Questions 19 to 21: the sticker, crayon and apple stories, each needing an equation with a symbol for the unknown.

2.OA.2

“Fluently add and subtract within 20 using mental strategies. By end of Grade 2, know from memory all sums of two one-digit numbers.”

Questions 1 to 18 stay within 20, from the twelve fluency facts to the missing-number puzzles.

What's inside this worksheet

Part 1: Fast Fact Fluency

Twelve mental math facts within 20, mixing sums like 9 + 9 with differences like 16 - 9. Students write the missing number for each.

Part 2: Missing Number Puzzles

Six equations with the unknown in different positions: 7 + ___ = 15, ___ - 6 = 8 and 14 - ___ = 5 among them.

Part 3: Story Problems

Maya's teacher gives her stickers and Jenna owns 19 fewer crayons than Caleb. Students write an equation with a symbol for the unknown before solving.

Part 4: Two-Step Super Challenge

Liam picks 34 apples on Saturday and 25 on Sunday, then his family bakes 18 into pies. Step 1 finds the total, step 2 finds the 41 left.

Answer key

Solutions for all 21 questions, with the related fact written beside each missing-number answer, such as 8 because 15 - 7 = 8.

How teachers use it

Fluency timer

Give Part 1 two minutes. Early finishers start the puzzles, so fast students stay busy while the rest work.

Spot the unknown position

Write 7 + ? = 15 and ? - 6 = 8 on the board before Part 2 and ask what changed. Students who see the unknown move can solve the rest alone.

Two-step scaffold

Part 4 prints Step 1 and Step 2 prompts. Cover them for strong students and let them plan the steps themselves.

More 2nd Grade Math worksheets

Place Value Measurement and Data Geometry Money and Time

Get started today

Create your own lesson plans, worksheets, and classroom activities in minutes using our AI-powered tools.

Try Chalkie for free