Project Grade 3 Engineering & Design

Brindlewood Cafeteria Grease Catcher: A Grade 3 Design Project

A five-session grade 3 project building a sink catcher for a fictional school kitchen, tested twice against stated flow, catch, and cleaning limits.

Grade: Grade 3
Subject: Engineering & Design
Material: Project
Time: 5 sessions, ~225 min total
Prep: Moderate prep
Materials: 1 plastic tub no wider than 20 centimeters per team, 1 piece of wire screen or mesh per team, 2 squares of cloth per team, About 10 cotton balls per team, About 1 cup of small aquarium gravel per team, 1 plastic bottle cap tray or egg carton lid per team, Rubber bands and masking tape, 1 measuring jug marked to 1 liter per team, 1 tablespoon of cooking oil per test, About 20 paper punch dots or small sponge bits per test, 1 stopwatch or timer per team, 1 clear catch bucket per team, Warm tap water, 1 liter per test, Photos of a kitchen rinse sink and its drain pipe, 1 lidded waste jar for used test water, A spoonful of solid shortening for the cooling demonstration

Standards

3-5-ETS1-1 NGSS

Define a simple design problem reflecting a need or a want that includes specified criteria for success and constraints on materials, time, or cost.

How this material aligns: Session 1 makes each team write three catch and flow goals plus five limits on materials, size, and cleaning time onto the design card before any building starts, the problem definition this standard requires.

All materials for 3-5-ETS1-1 →

3-5-ETS1-2 NGSS

Generate and compare multiple possible solutions to a problem based on how well each is likely to meet the criteria and constraints of the problem.

How this material aligns: Session 2 requires two labeled catcher sketches scored against the same three goals, with the chosen design circled and defended, the comparison of possible solutions this standard names.

All materials for 3-5-ETS1-2 →

3-5-ETS1-3 NGSS

Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved.

How this material aligns: Session 4 names the worst performing part, changes only that part, and retests with the same one liter of test water, the controlled fair test and prototype improvement this standard describes.

All materials for 3-5-ETS1-3 →

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This material is in the public domain (CC0) and may be copied, edited, and shared freely, without attribution. Updated 2026-09-23.

Objectives

Students will write three goals and five limits for a sink catcher.
Students will sketch two catchers and score both against the same goals.
Students will change one part after a test and retest the same way.
Students will present a design card to a client with test results.

Vocabulary

Key words: catcher, grease, goal, limit, prototype

Teacher overview

The driving question is how a class can build a catcher for the rinse sink in a fictional school kitchen that keeps food bits and cooking grease out of the pipe leading to the town's water cleaning plant. The project mirrors a real constraint that plant crews live with, because grease that cools inside a sewer pipe sticks to the walls and traps everything that follows, which is why many towns require kitchens to fit a catcher before the drain. Each team turns in a working catcher, a one-page design card, and a two-minute presentation to the kitchen manager. Third graders usually assume hot water sends grease harmlessly away, since it looks thin and moving in the sink, and the first test in Session 3 gives them a cooled catch bucket where the same grease is visible again.

Brindlewood Cafeteria Grease Catcher: A Grade 3 Design Project — Grade 3 Engineering & Design

Name: ____________________________ Date: ______________

Project Brief

The question. How can we build a catcher for the Brindlewood School rinse sink that keeps food bits and grease out of the pipe to the town plant?

Our client. The Brindlewood School kitchen manager. Your team will present to the manager in the last session.

What the catcher must do. These are your three goals.

Catch most of the food bits in the test water.
Catch the grease you can see on top of the test water.
Let the water keep flowing fast enough for a busy kitchen.

What you may not go past. These are your five limits.

Build only from the supply table. Nothing may come from home.
The catcher must fit inside a tub no wider than 20 centimeters.
One liter of test water must pass through in under 2 minutes.
One person must lift the catcher out and clean it in 3 minutes.
No part may be glued for good. The catcher must come apart.

The test water. Your teacher mixes 1 liter of warm water, about 20 paper dots that stand for food bits, and 1 tablespoon of cooking oil that stands for grease. Every team gets the same mix every time. After each test, pour the used water into your teacher's waste jar, never down a sink, and wipe up any oil spill right away so no one slips.

What you turn in. Your team turns in three things. The first is the working catcher. The second is a one-page design card with a labeled drawing, your three goals, your five limits, and both rows of test data. The third is a two-minute talk to the kitchen manager saying what you built and what your data shows.

Milestones

Session 1: Name the problem. Look at photos of the rinse sink and the pipe that leaves it. Talk about where grease goes when it cools. Write the three goals and the five limits on your design card in your own words. Output: the top half of the design card, checked by your teacher.
Session 2: Draw two and pick one. Each person sketches one catcher. The team then picks the two best sketches and labels the parts on both. Score each sketch against the three goals using yes, partly, or no. Circle the one you will build and write one sentence saying why. Output: two labeled sketches and a scoring table with the pick circled.
Session 3: Build and test once. Build your chosen catcher from the supply table. Pour the 1 liter of test water through it. Time how long the water takes to pass. Count the paper dots that got past. Look for shine on top of the catch bucket. Output: a built catcher and a filled Round 1 data row.
Session 4: Fix the weak part. Look at your Round 1 row and name the one part that did the worst job. Change only that part. Pour the same 1 liter of test water through again and record the new numbers. Output: a Round 2 data row and one sentence naming what you changed and why.
Session 5: Present to the client. Give a two-minute talk to the kitchen manager. Show the catcher. Read your two data rows. Say which goal you met best and which goal is still hard. Answer one question from the manager. Output: the talk given and the design card handed in.

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

Rubric

Criterion	Ready to build on	On target	Getting there	Not yet
Goals and limits on the design card	All three goals and all five limits are written clearly in the team's own words, and each limit is later referred to by name	All three goals and all five limits are written correctly	Some goals or limits are missing, or copied without meaning	Goals and limits are missing or mixed up with each other
Comparing two designs	Two labeled sketches are scored against all three goals, and the written reason for the pick names a goal and a limit	Two labeled sketches are scored against all three goals and one is picked with a reason	Only one sketch is made, or the scoring skips a goal	No comparison is made and a design is built straight away
Building within the limits	The catcher fits the tub, comes apart for cleaning, and uses only supply table parts, and the team can show how each limit was met	The catcher meets every limit	The catcher breaks one limit, such as size or coming apart	The catcher breaks more than one limit
Testing and improving	Both rounds use the same test water, only one part is changed, and the team explains what the change did to the numbers	Both rounds are run the same way and the change is named	Two rounds are run but more than one part changed at once	Only one round is run, or the data rows are blank
Presenting to the client	The talk gives both data rows, names the goal met best and the goal still hard, and answers the manager's question with evidence	The talk gives both data rows and names what the catcher does	The talk describes the catcher but skips the data	The talk is not given or has no connection to the design card

Differentiation

Support

Give these teams a design card with the five limits already printed so Session 1 is spent writing the three goals only. Pre-cut the screen and cloth to tub size, and provide a picture menu of four catcher layouts they can choose between in Session 2 instead of sketching from a blank page.

Extension

Ask these teams to add a sixth limit of their own that a real kitchen would care about, such as a catcher that does not smell by the end of the day, and to test against it. Have them run a third round in which they test whether their Session 4 change still works when the test water is poured twice as fast.

ELL supports

Pre-teach grease, catcher, goal, limit, and flow with the real objects on the supply table and a short demonstration of melted shortening hardening as it cools in a cup. Provide the frames "Our goal is ___" and "We changed the ___ because ___." Allow the design card drawing to carry labels in a first language with an English word added beside each one.

Extensions

Ask the school kitchen staff whether the building already has a grease catcher and how often it is cleaned. Teams can compare what they learn with their own design card and write one sentence saying which of their five limits the real device also has to meet.