Classroom activity Grade 6 Math

The Bucket Brigade Challenge: Calculating a Relay's Pumping Rate

A grade 6 relay activity where teams move cups of water between buckets, then calculate and convert their team's unit rate to gallons per minute.

Grade: Grade 6
Subject: Math
Material: Classroom activity
Time: 35 min
Prep: Low prep
Materials: 8-ounce cups (one consistent size for every team), 2 buckets per team (a source bucket and a destination bucket), Stopwatch or phone timer, Recording sheet, Towels for spills

Standards

6.RP.A.2 Common Core Math

Understand the concept of a unit rate a/b associated with a ratio a:b with b not equal to 0, and use rate language in the context of a ratio relationship.

How this material aligns: The recording sheet and debrief questions require finding the unit rate of cups transferred per second, exactly the unit rate a/b concept this standard defines.

All materials for 6.RP.A.2 →

6.RP.A.3 Common Core Math

Use ratio and rate reasoning to solve real-world and mathematical problems, e.g., by reasoning about tables of equivalent ratios, tape diagrams, double number line diagrams, or equations, including finding a percent of a quantity and converting measurement units.

How this material aligns: Step 7 has students convert their measured rate from cups per minute to gallons per minute using a given conversion, the measurement-unit conversion this standard names.

All materials for 6.RP.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 2026-07-16.

Objectives

Students will calculate a unit rate (cups per second) from a timed relay.
Students will convert a unit rate from cups per second to cups per minute and gallons per minute.
Students will compare how a change in technique affects a measured rate.

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: unit rate, conversion

Teacher overview

This is a timed relay activity for teams of 4 to 5 students. Each team moves water, one cup at a time, from a "source" bucket to a "destination" bucket set ten feet away, with each relay leg standing in for one segment of pipe carrying water from a treatment plant toward a neighborhood. After each round, teams calculate their own unit rate and convert it into gallons per minute, turning a physical relay into a genuine measurement task.

A common misconception during this activity is assuming that a team moving cups quickly always has the higher rate, when a team that rushes and spills may count fewer full cups than a slower, steadier team. The debrief is built to settle that question with the actual calculated rate rather than a visual impression.

Activity Directions

Explain the setup to the class: each relay leg represents a segment of pipe carrying water from a treatment plant (the source bucket) to a neighborhood tower (the destination bucket), and the team's "flow rate" is how fast they can move water through their simulated pipeline.
Divide the class into teams of 4 to 5 students. Give each team a source bucket filled with water, an empty destination bucket set ten feet away, and a stack of cups. Run the relay outdoors or on a floor where spills can be wiped up at once, and remind students to walk rather than run.
On "go," the first team member scoops one full cup of water, walks it to the destination bucket, pours it in, and returns to tag the next teammate, who repeats the process. Continue the relay until the timer ends.
Run each team for a timed 90-second round. When the timer ends, teams count how many full cups were successfully poured into the destination bucket. A spilled or partial cup does not count.
Each team records its total cups transferred and the round length (90 seconds) on the recording sheet.
Teams calculate their unit rate in cups per second by dividing their total cups by 90, then convert that rate to cups per minute by multiplying by 60.
Using the fact that 16 cups equal 1 gallon, each team converts its cups-per-minute rate to a gallons-per-minute rate by dividing by 16.
Give teams two minutes to discuss and adjust their relay order or technique, then run a second timed 90-second round. Teams recalculate their unit rate and compare it to round 1, discussing what changed the rate.
End the activity once every team has completed both rounds and recorded both unit rates. Gather the class at the front for the debrief.

The Bucket Brigade Challenge: Calculating a Relay's Pumping Rate — Grade 6 Math

Name: ____________________________ Date: ______________

Student Handout

Debrief questions. Work these out for the sample team below, then repeat the same three steps with your own team's recorded cup count.

A team transferred 45 full cups of water during a 90-second round. What is that team's unit rate in cups per second?
That same team transferred 45 full cups during a 90-second round. What is that team's rate in cups per minute?
That same team transferred 45 full cups during a 90-second round. Using the fact that 16 cups equal 1 gallon, what is that team's rate in gallons per minute?

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: 0.5 cups per second.
45 cups ÷ 90 seconds = 0.5 cups per second.
Answer: 30 cups per minute.
0.5 cups per second × 60 seconds per minute = 30 cups per minute.
Answer: 1.875 gallons per minute.
30 cups per minute ÷ 16 cups per gallon = 1.875 gallons per minute.

Differentiation

Support (below grade level)

Provide a printed conversion strip showing "cups ÷ seconds in the round = cups per second," "cups per second × 60 = cups per minute," and "cups per minute ÷ 16 = gallons per minute," and allow a calculator for every step. Reduce the round length to 60 seconds for an easier initial count.

Extension (above grade level)

Ask teams to calculate how many minutes it would take their round-1 rate to fill a 20-gallon container, and to compare that prediction with how many minutes it would take their round-2 rate to do the same.

ELL supports

Demonstrate the relay once, slowly, before teams begin, narrating each step aloud with simple language ("scoop, walk, pour, return, tag"). Provide the recording sheet with icons next to each blank (a cup icon for the count, a clock icon for the time) so the numeric entries are clear without relying on text alone.