Graphic organizer Grade 4 Engineering & Design
Choosing a Hand Pump for Brindlefield Garden: A Trade-Off Matrix
A grade 4 trade-off matrix organizer for picking one of three hand pumps for a fictional village garden well, with a rule-check grid and a completed exemplar.
Objectives
- Students will pull five features of three hand pumps out of a short meeting notice.
- Students will mark which pumps meet each stated rule and which pump meets all of them.
- Students will name what the garden club gives up by choosing the winning pump.
Vocabulary
Key words: trade-off, criteria, constraint, hand pump, treadle
Teacher overview
This organizer is a trade-off matrix: three designs down the side, the same five features across the top, and a second grid underneath where students check each design against the club's rules one rule at a time. The source is a short set of meeting notes from a fictional village garden, so every cell can be filled from the text rather than from outside knowledge. Fourth graders tend to pick whichever pump has the single best-looking number rather than the pump that satisfies every rule, which is why the rule-check grid is separate from the feature grid and why the last row asks what the winner costs the club. A pump that wins on price can still be the wrong pump when the well is deeper than that pump can reach.
Organizer
Read the notes. Then fill in both grids from the top down.
Notes from the Brindlefield Garden Club meeting
The garden club waters its beds from a shallow well. In the well, the water sits 12 feet below the ground. The old hand pump broke last fall. Three pumps are for sale.
Pump A is a lever pump. It can lift water from 15 feet down. It takes 12 pushes to fill a bucket. It costs 22 supply tokens. The handle is long and heavy, so it takes two hands and a tall reach. The hardware store in the village keeps spare parts on the shelf.
Pump B is a crank pump. It can lift water from 8 feet down. It takes 30 turns of the crank to fill a bucket. It costs 14 supply tokens. A fourth grader can turn it alone. Spare parts must be ordered and take 3 weeks to arrive.
Pump C is a treadle pump. It can lift water from 15 feet down. It takes 20 steps on the pedals to fill a bucket. It costs 24 supply tokens. A fourth grader can work it alone, and both hands stay free to hold the bucket. The hardware store keeps spare parts on the shelf.
The club wrote three rules. The pump must lift water from 12 feet down. A fourth grader must be able to work it alone. The club may spend no more than 25 supply tokens.
Grid 1: feature matrix
| Pump | How deep it can lift | Work to fill one bucket | Cost in supply tokens | Can a fourth grader work it alone? | Wait for spare parts |
|---|---|---|---|---|---|
| A: lever | |||||
| B: crank | |||||
| C: treadle |
Grid 2: rule check
Write yes or no in each box.
| Pump | Rule 1: lifts from 12 feet down | Rule 2: a fourth grader can work it alone | Rule 3: costs 25 tokens or fewer | Meets all three rules |
|---|---|---|---|---|
| A: lever | ||||
| B: crank | ||||
| C: treadle |
Decision rows
| Question | Your answer |
|---|---|
| Which pump do you recommend to the club? | |
| Which rule ruled out Pump A? | |
| Which rule ruled out Pump B? | |
| What does the club give up by choosing your pump? | |
| One thing the club should test before buying |
From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.
Completed Exemplar
Grid 1: feature matrix
| Pump | How deep it can lift | Work to fill one bucket | Cost in supply tokens | Can a fourth grader work it alone? | Wait for spare parts |
|---|---|---|---|---|---|
| A: lever | 15 feet | 12 pushes | 22 | no, it needs two hands and a tall reach | none, parts are on the shelf |
| B: crank | 8 feet | 30 turns | 14 | yes | 3 weeks |
| C: treadle | 15 feet | 20 steps | 24 | yes | none, parts are on the shelf |
Grid 2: rule check
| Pump | Rule 1: lifts from 12 feet down | Rule 2: a fourth grader can work it alone | Rule 3: costs 25 tokens or fewer | Meets all three rules |
|---|---|---|---|---|
| A: lever | yes | no | yes | no |
| B: crank | no | yes | yes | no |
| C: treadle | yes | yes | yes | yes |
Decision rows
| Question | Your answer |
|---|---|
| Which pump do you recommend to the club? | Pump C, the treadle pump, because it is the only pump that meets all three rules. |
| Which rule ruled out Pump A? | Rule 2. The lever handle takes two hands and a tall reach, so a fourth grader cannot work it alone. |
| Which rule ruled out Pump B? | Rule 1. The crank pump reaches only 8 feet down, and the water sits 12 feet down. |
| What does the club give up by choosing your pump? | Pump C costs 10 more supply tokens than Pump B, and it takes 20 steps to fill a bucket instead of the 12 pushes Pump A needs. |
| One thing the club should test before buying | Ask the store to set up the treadle pump so a few club members can try filling one bucket each and time how long it takes. |
Differentiation
Support
Fill Grid 1 in as a class, one column at a time, before students work on Grid 2 alone. Highlight the three rules in the notes with one color and the pump features with another, so students can see which sentence answers which box. For the decision rows, accept a circled pump name plus one phrase rather than a full sentence.
Extension
Ask students to add a sixth column to Grid 1 for a feature the notes never mention but the club would care about, such as how the pump handles a freezing night or how loud it is. Then have them explain, in two or three sentences, what they would need to learn about each pump to fill that new column honestly, and whether it could change the winner.
ELL supports
Pre-teach lever, crank, treadle, spare part, and bucket with sketches or classroom objects, and act out each motion so the three pumps feel different before any reading happens. Allow students to write feature cells as numbers and single words rather than phrases, and provide the sentence frame "Pump ____ is out because ____." for the two ruled-out rows.
Extensions
Give the class a fourth pump card with a mixed profile, such as a pump that lifts from 20 feet down, is easy for a fourth grader to work, and costs 31 supply tokens, and ask what the club should do when the best-performing pump is over the spending limit. Students can argue for raising the limit, for a fundraiser, or for staying with Pump C, and should point to a specific row of the matrix in each case.