Graphic organizer Grade 5 Engineering & Design
Wistman Row Storm Inlet: A Grade 5 Failure Point Chain
A grade 5 cause-effect chain organizer that turns a clogged model storm drain into a named failure point, a cause, two possible fixes, and a retest plan.
Objectives
- Students will name the exact failure point in a tested model, rather than calling the whole model a failure.
- Students will trace a test result back to a physical cause in the design.
- Students will propose two design changes and choose one, keeping the fair test intact.
Vocabulary
Key words: storm inlet, grate, failure point, controlled variable, retest
Teacher overview
This organizer is a six-link cause-effect chain, and it is meant to be filled in right after a model test goes wrong. The example running through it is a model storm inlet built for the fictional street of Wistman Row: a paper cup sunk into a sloped tray, with a slotted card taped over it as a grate. Water poured onto the tray ran to the grate, leaves piled against the slots, and the water backed up and ran past the inlet instead of down it. The chain moves a student from that observation to a named failure point, then to a cause, then to two possible design changes and a choice between them.
A misconception this organizer is built to correct: fifth graders almost always write "it didn't work" or "the design failed" in the result box and stop there. A failure point is narrower than that. It is the one part, at one moment, where the design stopped meeting its goal, and on Wistman Row it is the slots in the grate at the moment the leaves covered them, not the cup, not the tray, and not the pouring. Push students to name a part and a moment. If a student writes "the water went everywhere," ask what part of the model the water was touching when it first went the wrong way. Engineers keep this distinction because a design change aimed at the whole model is guesswork, while a change aimed at a named failure point can be tested against the same fair test as before.
Plan about 25 minutes: five minutes to review the test the class just ran, fifteen minutes to fill the six boxes, and five minutes to hear several chosen design changes and ask why each student picked the one they did.
Organizer
Fold a sheet of paper into six boxes, or print the frame, and draw an arrow from each box to the next. Fill the boxes in order. Short phrases are fine.
Box 1 — What we tested. Name the design and the one thing you were testing about it. Write one sentence.
Box 2 — What we kept the same. List three things you held steady so the test was fair, such as the amount of water, the tilt of the tray, and the place you poured from.
Box 3 — What we saw. Describe what the water actually did. Do not judge it yet. Write one or two sentences.
Box 4 — Failure point. Name the one part, and the one moment, where the design stopped doing its job. Finish this stem: "The design stopped working at the ___ , when ___ ."
Box 5 — Why it failed. Explain what about that part caused the problem. Think about size, shape, spacing, or the way the part was placed.
Box 6 — Design change. Write two changes you could make to that one part. Then circle the one you would test next, and write one sentence saying why you picked it. Below the circle, name what you will keep the same so your retest is still fair.
From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.
Completed Exemplar
| Link | Wistman Row storm inlet |
|---|---|
| 1. What we tested | A model storm inlet made from a cup set in a sloped tray, with a slotted card as the grate. We tested whether it could take in all the water from one pour while leaves were on the street. |
| 2. What we kept the same | The same 2 cups of water each time, the same tray tilt on one book, and the same pouring spot at the top of the tray. |
| 3. What we saw | Water reached the grate and went in at first. Then leaves gathered along the slots, and the water spread sideways and ran past the inlet down the tray. |
| 4. Failure point | The design stopped working at the slots in the grate, when the leaves lay flat across them and covered the openings. |
| 5. Why it failed | The slots were wide enough for water but flat and level, so a leaf could rest on top and seal them. There was no open space left once four or five leaves overlapped. |
| 6. Design change | Change one: cut the slots into a curved, dome-shaped grate so leaves slide off instead of lying flat. Change two: cut the slots longer and narrower, running downhill, so a single flat leaf cannot cover a whole slot. We circled the dome grate, because it stops the clog from forming instead of working around it. We will keep the water amount, the tray tilt, and the pouring spot the same on the retest. |
This exemplar shows what a complete chain looks like. Notice that box 4 names a part and a moment, that box 5 explains the shape of that part rather than blaming the leaves, and that box 6 keeps the fair test intact by changing the grate alone.
Differentiation
Support
Give these students boxes 1 and 2 already filled in, so the work starts at the observation. Offer a word bank for box 4 that lists the model's parts by name: tray, curb, grate, slot, cup, and outlet. A student who can point to the part on the physical model can usually name it on the page, so keep the model on the desk while they write.
Extension
Ask these students to run the retest they described in box 6 and then complete a second chain for the new design. They should compare the two chains side by side and write a short paragraph on whether the change moved the failure point somewhere else, which is a common and instructive result rather than a sign of a bad fix.
ELL supports
Provide the box 4 and box 6 stems as printed sentence strips students can complete with single words. Pair each box heading with a small icon drawn on the board: an eye for what we saw, a red dot for the failure point, and a wrench for the design change. Allow students to label a sketch of the model with arrows instead of writing full sentences in boxes 3 and 5.
Extensions
After a heavy rain has passed, students can look at a real storm grate near the school, with an adult and from the sidewalk, and note what has collected against it, then write a one-box chain link naming the failure point they would expect if that debris doubled. Many towns publish a leaf-collection schedule, and connecting that schedule to the chain shows students that one common answer to this design problem is not a new grate at all but a maintenance plan.