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Lesson plan Grade 5 Health & Consumer Science

Castlebrook Day Camp's Hydration Tank: Volume in Gallons

A grade 5 lesson in which students find the volume of a fictional camp's water tanks in cubic feet and convert those cubic feet into gallons.

Objectives

  1. Students will find the volume of a rectangular water tank by multiplying length, width, and depth.
  2. Students will convert a tank volume in cubic feet to gallons by multiplying by 7.48.
  3. Students will subtract and compare decimal gallon amounts to answer a camp hydration question.

Vocabulary

Key words: volume, cubic foot, gallon, hydration

Teacher overview

Summer camps, athletic fields, and outdoor work sites often store drinking water in a large rectangular tank rather than in individual bottles, so the person in charge of hydration has to know how much the tank actually holds. This lesson uses the fictional Castlebrook Day Camp, where staff fill camper bottles from two rectangular tanks, and it asks students to find each tank's volume in cubic feet and then convert that volume to gallons. One cubic foot holds 7.48 gallons, a standard conversion that appears on operator formula sheets. The misconception this lesson addresses is that a tank's volume in cubic feet is the same as its capacity in gallons, and a student who gives the same number for both has stopped before the conversion step.

Procedure

Launch (5 min): Stand a cardboard box on a desk and tell students it is a scale model of a camp water tank. Ask them what two questions the camp director would need answered before deciding whether the tank can supply a full day of drinking water. Steer the discussion toward how much space is inside and how many gallons that space holds.

Model the volume formula (12 min): Write V = length x width x depth on the board. Work a modeled example that students will not see again on the handout: a tank 2 feet long, 2 feet wide, and 3 feet deep has a volume of 2 x 2 x 3 = 12 cubic feet. Then show the conversion, 12 x 7.48 = 89.76 gallons, lining up the decimal point carefully and naming the hundredths place aloud. Record both steps in a two-column class volume table labeled "cubic feet" and "gallons."

Partner practice (8 min): Give partners one more teacher-directed problem to solve together on whiteboards: a tank 3 feet by 3 feet by 2 feet. Partners should report 18 cubic feet and 134.64 gallons. Collect answers with a quick whiteboards-up check; if more than a third of the pairs report 18 gallons instead of 134.64 gallons, stop and rebuild the conversion using the class table before moving on.

Independent handout (15 min): Students complete the eight-question handout on their own. Circulate and watch question 8, where two decimal amounts must be subtracted, and question 5, where a whole number is multiplied by 0.5.

Exit check (5 min): Collect the handouts. Ask each student to write on a sticky note which is larger for the same tank, the number of cubic feet or the number of gallons, and how they know. Use the sticky notes to sort students for the next day's support and extension groups.

Castlebrook Day Camp's Hydration Tank: Volume in Gallons — Grade 5 Health & Consumer Science
Name: ____________________________ Date: ______________

Student Handout

The Castlebrook Day Camp described here is fictional. Use 7.48 gallons for every 1 cubic foot.

  1. Castlebrook Day Camp's large water tank is shaped like a rectangular prism 5 feet long, 4 feet wide, and 3 feet deep. What is the volume of the tank in cubic feet?
  2. The large tank holds 60 cubic feet of water. One cubic foot holds 7.48 gallons. How many gallons does the large tank hold when it is full?
  3. A second rectangular tank at the camp is 6 feet long, 2 feet wide, and 3 feet deep. What is the volume of the second tank in cubic feet?
  4. The second tank holds 36 cubic feet. Using 7.48 gallons for each cubic foot, how many gallons does the second tank hold?
  5. The camp has 120 campers. Each camper fills one bottle that holds 0.5 gallon. How many gallons do the campers use for one round of filling?
  6. The large tank starts full with 448.8 gallons. The campers take out 60 gallons. How many gallons are left in the tank?
  7. The camp fills bottles 3 times a day, and each round of filling uses 60 gallons. How many gallons does the camp use in one day?
  8. The large tank holds 448.8 gallons and the second tank holds 269.28 gallons. How many more gallons does the large tank hold?

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: 60 cubic feet. Volume is length x width x depth, so 5 x 4 x 3 = 60.
  2. Answer: 448.8 gallons. Multiply the volume by the conversion: 60 x 7.48 = 448.8.
  3. Answer: 36 cubic feet. Volume is 6 x 2 x 3 = 36.
  4. Answer: 269.28 gallons. Multiply 36 x 7.48 = 269.28, keeping two decimal places.
  5. Answer: 60 gallons. Each of the 120 campers uses 0.5 gallon, and 120 x 0.5 = 60.
  6. Answer: 388.8 gallons. Subtract the amount taken out: 448.8 - 60 = 388.8.
  7. Answer: 180 gallons. Three rounds at 60 gallons each is 60 x 3 = 180.
  8. Answer: 179.52 gallons. Subtract the smaller capacity from the larger: 448.8 - 269.28 = 179.52.

Differentiation

Support

Give these students the volume already computed for questions 1 and 3 so the work begins at the conversion step, and let them use a calculator for the two multiplications by 7.48 while they record the setup by hand. Build one cubic foot out of paper or point to a one-foot cube in the room so the unit stays physical rather than abstract.

Extension

Ask students to design a third rectangular tank for the camp that would hold at least 500 gallons, state its length, width, and depth in whole feet, and show the two calculations that prove the capacity meets the target. Students should also explain why more than one set of dimensions can work.

ELL supports

Pre-teach "volume," "cubic foot," and "gallon" with the cardboard box, a one-foot cube, and a gallon jug set side by side, and post the sentence frame "The tank holds ____ cubic feet, which is ____ gallons." Allow students to record answers as labeled numbers in the class table format rather than in full sentences, and pair them with a partner for a spoken rehearsal of question 2 before writing.

Extensions

Students can measure a real container at school, such as a recycling bin or a storage tub, in feet and tenths of a foot, then estimate its capacity in gallons using the same two steps. Comparing the estimate to the capacity printed on the container gives a natural discussion of measurement error and rounding.