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Classroom activity Grade 3 Science

Garrowmoor's Dry Month: A Grade 3 Reservoir Gauge Game

A 45-minute grade 3 team game where students track a fictional town's reservoir gauge through four dry weeks and play saving cards to finish far above the line.

Objectives

  1. Students will subtract weekly water use and add weekly rain to track a reservoir gauge across four weeks.
  2. Students will choose saving cards and show how much higher the gauge ends because of those choices.
  3. Students will state one criterion for success and one constraint for the town's water problem.

Vocabulary

Reservoir
A human-made lake, usually created by a dam, that stores water for later. Reservoirs supply cities and farms and help control floods.
Drought
A long stretch of drier-than-normal weather that leaves too little water for people, farms, and nature. Droughts build slowly and can last for years.

Also: gauge, criteria, constraint, water use

Teacher overview

This is a four-round team game for groups of four, played with a paper gauge strip and two small decks of cards. The gauge stands for the water level in the reservoir that serves the fictional town of Garrowmoor, and every round the level drops by the week's water use and rises by whatever rain falls. Teams cannot change how much rain falls, so their only choice is which saving cards to play, and those cards reduce the town's use rather than adding water to the reservoir. A utility in a long dry summer works under the same limits. A misconception worth naming is that saving water "makes more water," when in fact it only slows the drop.

Activity Directions

  1. Setup (8 min). Print one gauge strip per team, marked from 0 cm to 250 cm in steps of 10 cm, with a heavy line drawn at 100 cm. Print one set of four week cards and one set of five saving cards per team. Form teams of four and give each team a strip, a card set, a counter, and one copy of the handout per student.
  2. Explain the gauge (4 min). Tell teams that the fictional Garrowmoor Reservoir starts the month at 240 cm. Place the counter at 240 cm. Explain that each week the level drops by the town's water use and rises by the week's rain.
  3. Read the week cards (3 min). Week 1 says use 60 cm, rain 15 cm. Week 2 says use 55 cm, rain 0 cm. Week 3 says use 40 cm, rain 10 cm. Week 4 says use 35 cm, rain 25 cm. Read all four aloud so no team is surprised later.
  4. Read the saving cards (3 min). The five saving cards are shorter showers, which saves 8 cm; fix the leaks, which saves 12 cm; no lawn watering, which saves 20 cm; wash cars less often, which saves 5 cm; and reuse rinse water on the garden, which saves 10 cm.
  5. Play four rounds (14 min). In each round a team may play at most two saving cards. A card that has been played is set aside and cannot be used again. The team subtracts any savings they played from the week's use, subtracts that new use from the gauge, adds the week's rain, and moves the counter to the new reading. Every player records the new reading in the recording table at the top of the handout.
  6. Ending condition (1 min). The game ends after round 4. The class gives a round of applause to every team whose counter finishes at or above the heavy 100 cm line.
  7. Complete the handout (8 min). Students work through the numbered handout questions, which use the same week cards but a set of readings given in the questions, so every student can check the arithmetic even if the team played different cards.
  8. Write the problem statement (2 min). Each team writes one sentence naming the town's problem, one sentence naming a criterion for success, and one sentence naming a constraint they had to work within.
  9. Debrief (2 min). Ask the whole class two questions: which saving card moved the gauge the most, and what would have happened in week 2 if no team had been allowed to play any card. Close by pointing out that no card added water to the reservoir, since every card only slowed the drop.
Garrowmoor's Dry Month: A Grade 3 Reservoir Gauge Game — Grade 3 Science
Name: ____________________________ Date: ______________

Student Handout

Record your team's game here.

Round Cards played Savings (cm) New reading (cm)
1
2
3
4

The fictional Garrowmoor Reservoir starts the month at 240 cm on the gauge. The town wants the gauge to stay at 100 cm or higher.

Week Water use Rain
1 60 cm 15 cm
2 55 cm 0 cm
3 40 cm 10 cm
4 35 cm 25 cm
  1. The gauge starts at 240 cm. In week 1 the town uses 60 cm and rain adds 15 cm. What does the gauge read at the end of week 1?
  2. Week 2 starts at 195 cm. The town uses 55 cm and no rain falls. What does the gauge read at the end of week 2?
  3. Week 3 starts at 140 cm. The town uses 40 cm and rain adds 10 cm. What does the gauge read at the end of week 3?
  4. Week 4 starts at 110 cm. The town uses 35 cm and rain adds 25 cm. What does the gauge read at the end of week 4?
  5. The town wants the gauge at 100 cm or higher. The week 4 reading is 100 cm. Does the town meet its goal?
  6. A team plays two cards in week 2. Fix the leaks saves 12 cm. No lawn watering saves 20 cm. How many centimeters do the two cards save together?
  7. Week 2 use was 55 cm. The two cards save 32 cm. What is the new week 2 use?
  8. Week 2 starts at 195 cm. The new use is 23 cm and no rain falls. What does the gauge read at the end of week 2 now?
  9. With the cards the week 2 reading is 172 cm. Without the cards it is 140 cm. How many centimeters higher is the reading with the cards?
  10. Write one thing the town must do for this month to count as a success.
  11. Write one rule or limit your team could not change during the game.

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: 195 cm. 240 minus 60 is 180, and 180 plus 15 is 195 cm.
  2. Answer: 140 cm. 195 minus 55 is 140, and no rain is added.
  3. Answer: 110 cm. 140 minus 40 is 100, and 100 plus 10 is 110 cm.
  4. Answer: 100 cm. 110 minus 35 is 75, and 75 plus 25 is 100 cm.
  5. Answer: Yes. The goal is 100 cm or higher, and the reading is exactly 100 cm, so the town just meets it.
  6. Answer: 32 cm. 12 plus 20 is 32 cm.
  7. Answer: 23 cm. 55 minus 32 is 23 cm.
  8. Answer: 172 cm. 195 minus 23 is 172 cm, and no rain is added.
  9. Answer: 32 cm. 172 minus 140 is 32 cm, which matches the savings from item 6.
  10. Answer: Keep the gauge at 100 cm or higher through week 4. Accept any criterion stated as a measurable target, such as finishing above the heavy line or never dropping below 100 cm during the month.
  11. Answer: The team cannot make it rain. Accept any real constraint from the game, including the four-week limit, the five saving cards available, the limit of two cards per week, or the fact that a card once played cannot be used again.

Differentiation

Support

Give these students a gauge strip with the starting reading and the week 1 result already marked, and let them use counters to model each subtraction ten at a time. Assign handout items 1 through 5, and read each week card aloud as the round begins. Pair each student with a partner who records while they move the counter.

Extension

Ask students to design a fifth week card for the fictional Garrowmoor game that keeps the final reading at exactly 120 cm, then show the arithmetic that proves it works. They should also rank the five saving cards from most to least helpful and explain the ranking with numbers from their recording table.

ELL supports

Pre-teach "reservoir," "gauge," "use," and "rain" with a clear jar marked in centimeters that you pour from and add to as you say each word. Provide the frames "The gauge starts at ___ cm" and "We used ___ cm, so the gauge dropped to ___ cm." Allow items 10 and 11 to be answered orally to a partner before writing.