Classroom activity Grade 4 Math
Larkspur Storm Drain Brigade: A Timed Litter-Removal Relay
A grade 4 relay activity where teams race a storm timer to clear litter tokens from model storm drains, multiplying totals and dividing a team's haul with a remainder.
Objectives
- Students will multiply the number of drains by tokens per drain to predict a team's maximum possible total.
- Students will divide a team's collected tokens evenly among team members and interpret the remainder.
Vocabulary
- Storm drain
- A storm drain is the grate at the edge of a street that swallows rainwater and sends it through pipes to the nearest creek or river. That water is usually not treated, so only rain belongs down the drain.
Also: runoff, pollution, remainder
Teacher overview
This is a timed relay activity for the whole class, played in teams of 4 students, built around a set of four model "storm drain" stations for each team, set up in the fictional town of Larkspur. Each drain is stocked with paper litter tokens that represent trash sitting where rain could wash it into Larkspur Creek, and teams race a countdown timer, standing in for an approaching storm, to clear every drain before time runs out. The relay's rule directly teaches the water-pollution concept behind it: litter still at a drain when the timer ends represents litter that would wash into the creek in a real storm, so clearing drains quickly and completely is exactly what keeps a real waterway cleaner.
Activity Directions
Before class, set up 4 "storm drain" stations for each team around the room using hula hoops or taped circles, and stock each one with 6 paper litter tokens (small torn paper scraps labeled "trash").
Divide the class into teams of 4 students. Explain the scenario: a storm is coming to Larkspur, and any litter tokens still sitting at a drain when the timer ends will "wash into Larkspur Creek."
Explain the math before starting: each team must visit all 4 of its own drains, in any order, and clear every token from a drain before moving to the next one. Model on the board: 4 drains × 6 tokens per drain = 24 tokens is the most a team could possibly clear if they reach and empty every drain.
Set a timer for 12 minutes to represent the storm's approach. At "go," each team sends members to drains, collecting tokens by hand into their team's bucket, moving to a new drain only after fully clearing the one they are at. Students walk quickly between drains rather than run, and step around the hoops.
When the timer ends, all teams freeze in place. Each team counts the tokens in its bucket and records the number on its team tally sheet. Any tokens still sitting at a team's drains are not counted for any team; they represent litter that "washed into the creek."
As a class, add together every team's token count to find the total litter kept out of the creek that round, and compare it to the total possible if every team had cleared every drain, to see how close the class came to a perfect round.
For the closing tally, have one team split its collected tokens evenly among its 4 members to take home as reminders of the activity. If the total does not divide evenly, discuss as a class what to do with the leftover tokens (for example, save them for a class collage about stormwater pollution).
End the activity once the closing tally and debrief questions are complete; work through the three numbered questions on the Student Handout as a class, then check each answer against the Answer Key.
Student Handout
Answer these three questions with your team after the round ends. Each question uses numbers from the Larkspur storm-drain relay you just played, so read it carefully and show your work.
Every drain starts with 6 litter tokens, and each team must clear all 4 drains. If 5 teams each cleared all 4 drains completely, how many tokens would the 5 teams collect in total?
Suppose the class actually collected 108 tokens out of the 120 that were possible in question 1. How many tokens were left at the drains when the storm timer ended?
One team collected 22 tokens and needs to split them evenly among its 4 members. How many tokens does each member get, and how many tokens are left over?
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: 120 tokens.
Debrief question: "How many tokens would 5 teams collect in total if every team cleared all 4 drains completely?" 5 teams × 24 tokens per team = 120 tokens.Answer: 12 tokens.
Debrief question: "If the class actually collected 108 tokens out of the possible 120 from question 1, how many tokens were left at the drains when the storm timer ended?" 120 − 108 = 12 tokens.Answer: 5 tokens each, 2 left over.
Debrief question: "One team collected 22 tokens and needs to split them evenly among its 4 members. How many tokens does each member get, and how many are left over?" 22 ÷ 4 = 5 remainder 2 (4 × 5 = 20, and 22 − 20 = 2), so each member gets 5 tokens, with 2 left over for the class collage.
Differentiation
Support (below grade level)
Reduce the number of drains to 2 for a support group's round, or lower the tokens per drain to 4, so the multiplication and division stay within easier facts while the same mechanic and debrief questions still apply. Pair students who need extra support with a partner during the relay itself.
Extension (above grade level)
Ask students to design a fifth drain with a different number of tokens so that the new class-wide maximum (5 teams × new total per team) lands exactly on a multiple of 25, and to show the multiplication that proves their design works.
ELL supports
Use picture labels at each drain station (a raindrop icon and a trash icon) so the scenario is clear without relying only on spoken directions. Provide a sentence frame for the debrief: "Our team collected ___ tokens, which is ___ tokens away from the possible total of ___."