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Math problem set Grade 3 Math

Ashgrove's Bottled Water Tables: A Grade 3 Two-Step Problem Set

While a fictional town repairs a broken water main, students use two-step multiplication and subtraction to track crates of bottled water handed out at the school gym.

Objectives

  1. Students will solve two-step word problems using multiplication and subtraction.
  2. Students will write an equation with a letter standing for the unknown amount.
  3. Students will judge whether a rounded estimate is close to an exact answer.

Vocabulary

Key words: crate, equation, unknown, estimate

Teacher overview

Ashgrove is a fictional town that hands out bottled water in the school gym for two days while a crew repairs a broken water main, and every count in this set comes from that one giveaway. Utilities really do stage bottled water this way during a main repair, so the crates, tables, and running totals supply a plain setting for two-step arithmetic. The misconception this set targets is stopping after the first step: a student who multiplies 7 crates by 6 bottles and writes 42 in problem 3 has found the bottles that arrived, not the bottles that are left. Each two-step solution below names the two steps separately so partial credit is easy to award.

Ashgrove's Bottled Water Tables: A Grade 3 Two-Step Problem Set — Grade 3 Math
Name: ____________________________ Date: ______________

Problems

A water main broke in the town of Ashgrove. The town hands out bottled water in the school gym. Each crate holds 6 bottles. For each problem, write an equation with a letter for the unknown, then solve.

  1. The crew brings in 8 crates. Each crate holds 6 bottles. How many bottles is that?
  2. Families take 15 bottles from those 8 crates. How many bottles are left?
  3. A second table starts with 7 crates of 6 bottles. Families take 12 bottles from it. How many bottles are left on the second table?
  4. On Tuesday the crew sets out 9 crates of 6 bottles. Then it adds 5 loose bottles. How many bottles are on the table now?
  5. At the end of the day the crew has 54 loose bottles. It packs them into crates of 6. How many crates does the crew fill?
  6. The gym has 4 tables. Each table gets 8 bottles. Then families take 6 bottles in all. How many bottles are on the tables now?
  7. A helper carries 3 crates of 6 bottles to the gym. The helper carries 2 more crates of 6 bottles to the library. How many bottles did the helper carry?
  8. The crew needs 90 bottles for Wednesday. It has 8 crates of 6 bottles. How many more bottles does the crew need?
  9. Nina says 9 crates of 6 bottles is about 60 bottles. How many bottles is 9 crates of 6 bottles?

From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.

Answer Key
  1. Answer: 48 bottles. There are 8 crates with 6 bottles in each crate, so 8 × 6 = b and b = 48 bottles.
  2. Answer: 33 bottles. Step one: 8 × 6 = 48 bottles arrived. Step two: 48 − 15 = 33 bottles are left.
  3. Answer: 30 bottles. Step one: 7 × 6 = 42 bottles arrived. Step two: 42 − 12 = 30 bottles are left. A student who writes 42 stopped after the first step.
  4. Answer: 59 bottles. Step one: 9 × 6 = 54 bottles in crates. Step two: 54 + 5 = 59 bottles in all.
  5. Answer: 9 crates. Divide the loose bottles into groups of 6: 54 ÷ 6 = c and c = 9 crates. Check by multiplying: 9 × 6 = 54 bottles.
  6. Answer: 26 bottles. Step one: 4 × 8 = 32 bottles were set out. Step two: 32 − 6 = 26 bottles are on the tables.
  7. Answer: 30 bottles. Step one: 3 × 6 = 18 bottles to the gym and 2 × 6 = 12 bottles to the library. Step two: 18 + 12 = 30 bottles. Students may also see 5 crates in all, and 5 × 6 = 30 bottles.
  8. Answer: 42 bottles. Step one: 8 × 6 = 48 bottles on hand. Step two: 90 − 48 = 42 more bottles are needed.
  9. Answer: 54 bottles. The exact product is 9 × 6 = 54 bottles. Nina's 60 is what 10 crates would hold (10 × 6 = 60), which is close but 6 bottles too many, so her estimate is reasonable for planning yet not exact enough for the count.

Differentiation

Support

Give students a two-box recording strip labeled "Step 1: how many came in" and "Step 2: how many now," and require both boxes before an answer counts as finished. Provide six-square crate cards students can draw on for problems 1 through 4. Work problem 3 together as a class, stopping to ask what the 42 stands for before anyone subtracts.

Extension

Ask students to write their own two-step problem about a third table in the gym, using a crate size other than 6 and keeping every product at or below 100, then trade problems with a partner and solve. Have them include the equation with a letter and a short check that shows the answer is reasonable.

ELL supports

Pre-teach "crate," "loose," "in all," and "left" with real containers and a stack of empty bottles. Post the sentence frames "First I found ___ bottles." and "Then I found ___ bottles." so the two steps are named separately. Allow students to draw the crates for problem 7 rather than writing an explanation.

Extensions

Have small groups plan the Wednesday giveaway for the same gym, deciding how many crates to bring if the town expects 120 bottles to be taken and each crate still holds 6 bottles. Ask them to show the division, state how many crates are needed, and explain what happens to the plan if only 15 crates arrive on the truck.