Worksheet Grade 4 Math

Redgrove's Hydrant Flushing Day: Gallons and Minutes

A grade 4 worksheet where students multiply flow rate by minutes open for four fictional fire hydrants, then compare, total, and plan the crew's schedule.

Grade: Grade 4
Subject: Math
Material: Worksheet
Time: 30 min
Prep: No prep
Materials: None

Standards

4.NBT.B.5 Common Core Math

Multiply a whole number of up to four digits by a one-digit whole number, and multiply two two-digit numbers, using strategies based on place value and the properties of operations. Illustrate and explain the calculation by using equations, rectangular arrays, and/or area models.

How this material aligns: Items 1 through 4 multiply a three-digit gallons-per-minute figure by a one-digit number of minutes for each of the four hydrants in the table.

All materials for 4.NBT.B.5 →

4.OA.A.3 Common Core Math

Solve multistep word problems posed with whole numbers and having whole-number answers using the four operations, including problems in which remainders must be interpreted. Represent these problems using equations with a letter standing for the unknown quantity. Assess the reasonableness of answers using mental computation and estimation strategies including rounding.

How this material aligns: Items 6 through 9 chain comparison, addition, and division across the four hydrant totals to answer questions about the crew's whole flushing day.

All materials for 4.OA.A.3 →

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This material is in the public domain (CC0) and may be copied, edited, and shared freely, without attribution. Updated 2026-09-03.

Objectives

Students will multiply a three-digit flow rate by a one-digit number of minutes to find total gallons.
Students will add four four-digit totals and compare two of them by subtraction.
Students will divide a hydrant count by a daily testing rate to find the number of days a job takes.

Vocabulary

Flow rate: Flow rate measures how much water moves past a point in a certain amount of time, like gallons per minute through a garden hose. Bigger pipes and stronger pushes give bigger flow rates.

Also: hydrant, flushing, total, crew

Teacher overview

Once a year the crew in the fictional town of Redgrove opens each fire hydrant for a few minutes and lets water run into the street, a job called flushing that pushes settled rust and grit out of the pipes. The crew records two numbers at every hydrant, the gallons it sends out each minute and the minutes it stayed open, and the total gallons come from multiplying the two. The misconception this worksheet is built to correct is the assumption that the hydrant with the largest flow rate must have released the most water: Hydrant 2 has the highest rate in the table yet Hydrant 4 releases more gallons, because it stayed open two minutes longer. Watch also for students who add the two columns instead of multiplying them.

Redgrove's Hydrant Flushing Day: Gallons and Minutes — Grade 4 Math

Name: ____________________________ Date: ______________

Student Worksheet

The Redgrove crew flushed four hydrants. Here is the crew's log.

Hydrant	Street	Gallons each minute	Minutes open
1	Mill Row	250	6
2	Larch Street	400	5
3	Quarry Lane	180	9
4	Harbor Road	320	7

Hydrant 1 sends out 250 gallons each minute. It stayed open 6 minutes. How many gallons came out?
Hydrant 2 sends out 400 gallons each minute. It stayed open 5 minutes. How many gallons came out?
Hydrant 3 sends out 180 gallons each minute. It stayed open 9 minutes. How many gallons came out?
Hydrant 4 sends out 320 gallons each minute. It stayed open 7 minutes. How many gallons came out?
Look at your four answers. Which hydrant sent out the most water?
Hydrant 4 sent out 2,240 gallons. Hydrant 1 sent out 1,500 gallons. How many more gallons did Hydrant 4 send out?
The four hydrants sent out 1,500 gallons, 2,000 gallons, 1,620 gallons, and 2,240 gallons. How many gallons is that in all?
Redgrove has 96 hydrants in all. On a full day the crew flushes 6 hydrants. How many full days will the whole job take?
Every hydrant test needs 15 minutes of setup. Hydrant 3 stayed open 9 minutes. How many minutes did that test take in all?
The crew writes down the gallons each minute and the minutes open. Explain why both numbers are needed. Write one or two sentences.

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

Answer Key

Answer: 1,500 gallons.
Multiply 250 by 6. Break it into parts: 200 times 6 equals 1,200 and 50 times 6 equals 300. Adding 1,200 plus 300 gives 1,500 gallons.
Answer: 2,000 gallons.
Multiply 400 by 5. Since 4 times 5 equals 20, four hundreds times 5 equals 20 hundreds, which is 2,000 gallons.
Answer: 1,620 gallons.
Multiply 180 by 9. Break it into parts: 100 times 9 equals 900 and 80 times 9 equals 720. Adding 900 plus 720 gives 1,620 gallons.
Answer: 2,240 gallons.
Multiply 320 by 7. Break it into parts: 300 times 7 equals 2,100 and 20 times 7 equals 140. Adding 2,100 plus 140 gives 2,240 gallons.
Answer: Hydrant 4.
Compare the four totals: 1,500 gallons, 2,000 gallons, 1,620 gallons, and 2,240 gallons. Hydrant 4's total of 2,240 gallons is the largest, even though Hydrant 2 has the higher flow rate, because Hydrant 4 stayed open two minutes longer.
Answer: 740 gallons.
Subtract 1,500 from 2,240. Take away 1,000 to reach 1,240, then take away 500 to reach 740 gallons.
Answer: 7,360 gallons.
Add in order. 1,500 plus 2,000 is 3,500. Then 3,500 plus 1,620 is 5,120. Then 5,120 plus 2,240 is 7,360 gallons.
Answer: 16 days.
Divide 96 by 6. Since 6 times 16 equals 96, the crew needs exactly 16 days with no hydrants left over.
Answer: 24 minutes.
Add the setup time to the time the hydrant was open: 15 plus 9 equals 24 minutes.
Answer: One number alone does not give the total.
Accept any explanation stating that the gallons each minute tells how fast the water comes out while the minutes open tells how long it ran, and that the total gallons come from multiplying the two, so a fast hydrant open for a short time can release less water than a slower one left open longer.

Differentiation

Support (below grade level)

Provide a partly completed version of the log in which item 1 is already worked as a labeled area model, with 200 times 6 and 50 times 6 shown in separate boxes. Give students a multiplication chart through 12 for the basic facts and allow them to solve only items 1, 2, 6, and 9. A number line marked in hundreds helps with the subtraction in item 6.

Extension (above grade level)

Ask students to plan a second flushing day for the fictional town of Redgrove in which four more hydrants release a combined total between 6,000 and 7,000 gallons. Students choose a flow rate and a number of minutes for each hydrant, show the multiplication for all four, prove the combined total falls in the range, and explain which pair of numbers they adjusted last and why.

ELL supports

Pre-teach "hydrant," "flushing," and "flow rate" with a labeled drawing of a fire hydrant with water running from an open port into a street gutter, marked with an arrow and the words "gallons each minute." Provide sentence frames for items 5 and 10: "Hydrant ___ sent out the most water because ___," and "The crew needs both numbers because ___." Allow item 10 to be answered orally to a partner before writing.

Extensions

Students can map the four Redgrove streets on grid paper and mark a route that visits all four hydrants, then use their totals to label how much water was released at each stop. A class ready for more can compare the flushing log with a real utility's published flushing notice, noting what information the utility chooses to publish for residents, such as dates, streets, and advice about discolored water, and why that choice makes sense.