Math problem set Grade 3 Math

Cedar Hollow's Leak Repairs: A Grade 3 Scaled Picture Graph Set

Students read a fictional town's picture graph of leaks fixed in five neighborhoods, where one drop stands for five leaks, then redraw rows at the same scale.

Objectives

  1. Students will read a picture graph in which one symbol stands for five items.
  2. Students will solve how-many-more and put-together problems from a scaled graph.
  3. Students will decide how many symbols a new graph row needs at a given scale.

Vocabulary

Key words: picture graph, scale, symbol, leak

Teacher overview

Cedar Hollow is a fictional town whose water crew keeps a running count of the leaking pipes it repairs in each neighborhood, and the town clerk posts that count as a picture graph on the library wall. Because the month's total runs past a hundred leaks, the graph uses a scale in which one drop stands for five repaired leaks, which is the scaled-graph reading grade 3 introduces. The misconception this set targets is counting symbols instead of reading the scale, so a row of seven drops gets reported as seven leaks rather than thirty-five. Problem 10 puts that error in front of students directly, and problems 7 through 9 ask them to work backward from a leak count to a number of drops.

Answer Key

  1. Answer: 30 leaks. There are 6 drops, and each drop stands for 5 leaks, so 6 × 5 = 30 leaks.
  2. Answer: 35 leaks. There are 7 drops, so 7 × 5 = 35 leaks.
  3. Answer: 15 leaks. There are 3 drops, so 3 × 5 = 15 leaks.
  4. Answer: 20 leaks. Fox Hill had 35 leaks and Birch Row had 15 leaks, so 35 − 15 = 20 leaks.
  5. Answer: 45 leaks. Center Street had 4 × 5 = 20 leaks and Stone Mill had 5 × 5 = 25 leaks, so 20 + 25 = 45 leaks.
  6. Answer: 125 leaks. The five rows hold 30 + 20 + 35 + 15 + 25 leaks. Add in order: 30 + 20 = 50, 50 + 35 = 85, 85 + 15 = 100, and 100 + 25 = 125 leaks.
  7. Answer: 8 drops. Each drop stands for 5 leaks, so divide: 40 ÷ 5 = 8 drops. Check by multiplying: 8 × 5 = 40 leaks.
  8. Answer: 6 squares. Maple Ridge had 30 leaks and each square stands for 5 leaks, so 30 ÷ 5 = 6 squares. The bar is the same height as the number of drops in the picture graph row.
  9. Answer: 7 drops. Birch Row had 15 leaks and Center Street had 20 leaks, so the new row stands for 15 + 20 = 35 leaks. Then 35 ÷ 5 = 7 drops.
  10. Answer: 35 leaks. Marla counted the drops instead of using the scale. Each drop stands for 5 leaks, so the 7 drops mean 7 × 5 = 35 leaks.

Differentiation

Support

Give students a copy of the graph with a small key printed beside every row, reading "1 drop = 5 leaks," and let them write 5, 10, 15, 20 under the drops as they skip-count across a row. Have them finish problems 1 through 3 before moving on, since the later items reuse those three totals. A hundred chart supports the addition in problem 6.

Extension

Ask students to redraw the whole graph at a scale where one drop stands for 10 leaks, decide which rows can no longer be drawn with whole drops, and write two sentences explaining why the town clerk chose a scale of 5 instead. Then have them state how many drops Stone Mill would need if the crew fixed 15 more leaks there.

ELL supports

Pre-teach "leak," "row," "scale," and "stands for" with a labeled drawing of one graph row and a dripping pipe. Post the sentence frame "___ drops stand for ___ leaks." Allow students to answer problem 10 by circling the correct number on a number line marked in fives rather than writing a full sentence.

Extensions

Have students collect a real class data set with values large enough to need a scale, such as the number of minutes each group spent at the classroom sink over a week. Ask them to choose a scale of 5, draw the picture graph, and then trade graphs with another group to check that the reader gets the same totals the makers intended.