Maryland Math 3.AT.A.2

3.AT.A.2 is a cluster heading. These are the individual standards under it.

• 3.AT.A.2.a

  Represent these problems using equations with a letter standing for the unknown quantity.

• 3.AT.A.2.b

  Assess the reasonableness of answers in terms of context, using mental computation and estimation strategies including, rounding, front-end estimation, and benc...

01

What Students Need to Do

Students solve story problems that take two steps, using addition, subtraction, multiplication, or division. They write an equation with a letter for the missing number. They estimate to check whether the answer fits the story.

02

What Mastery Looks Like

For 4 packs of 6 pencils with 5 given away, a student writes 4 × 6 − 5 = p and finds p = 19. They estimate that about 20 remain and reject an answer greater than the 24 they started with.

03

Common Misconceptions

Students may stop after finding the total in the packs and forget to subtract. Some use the letter as a label for pencils, not as the number missing from the equation. Others accept an answer larger than the starting amount even though items were taken away.

04

How to Assess It

Exit ticket: Three trays each hold 8 muffins, and 7 muffins sell. Write an equation using m for muffins left, solve it, and estimate to check your answer.

1. 01

   Give pairs 32 counters: share 24 among 4 cups, then add 2 to each cup and write 24 ÷ 4 + 2 = c.

2. 02

   Ask: 'Five packs hold 8 stickers each, and 6 are given away. Can 46 remain? How do you know without exact calculation?'

3. 03

   Play card match with '4 bags of 6 apples, 5 sold' and '4 × 6 − 5 = a'; solve before keeping the pair.

4. 04

   For a snack order, compare 40 bananas with 3 classes requesting 12 each; write 3 × 12 + b = 40 and find b.

• 7.NOS.A.3

  Solve multistep problems involving positive and negative rational numbers in any form (i.e., fractions, decimals, percents) using all four operations.

• 4.GR.A.2

  Use the four operations to solve problems in context involving distances, intervals of time, liquid volumes, masses of objects, and money, including problems in...

• 4.AT.A.4

  Solve multistep problems in context involving whole numbers and having whole number answers using the four operations, including problems in which remainders mu...

• 2.AT.A.2

  Use addition and/or subtraction within 100 to solve two-step problems in context involving any situation or position of an unknown by using objects, drawings, a...