Graphic organizer Grade 7 Health & Consumer Science
Verrell Farms to the Lunch Tray: An Irrigation Safety Chain
A six-link cause-and-effect organizer tracing how germs can move from a fictional pasture into irrigation water and onto school salad, with a control step for each link.
Objectives
- Students will trace a six-step path by which germs can move from pasture runoff to a school lunch tray.
- Students will name one control step that breaks each link in the chain.
- Students will explain in writing which link they would break first and why.
Vocabulary
- Drip irrigation
- Watering plants through tubes that release water slowly, drop by drop, right at the roots. Very little water is wasted along the way.
Also: irrigation, runoff, buffer strip, contamination
Teacher overview
This organizer is a cause-and-effect chain with six links, and it maps how germs can travel from a pasture into irrigation water and then onto food that students eat. The scenario is fictional: Verrell Farms grows lettuce beside Dowsett Ditch and ships it to the Colton Vale school kitchen. Each link gets a control step in the last column, and that column carries the health reasoning, because a farm, a driver, and a school kitchen each control a different link. Teaching note: washing produce at home is often assumed to remove any contamination, so the exemplar states plainly that rinsing lowers risk without erasing it, which is why food safety rules put most of their weight on the earlier links in the chain.
Organizer
Fill in the chain from top to bottom. Each row is one link. The arrows show that what happens in one link feeds the next.
Pasture → Ditch → Sprinklers → Harvest → Delivery → Lunch tray
| Link | What happens here | How germs could reach the food | What breaks this link |
|---|---|---|---|
| 1. Rain falls on the pasture above Dowsett Ditch | |||
| 2. Ditch water is pumped into the irrigation line | |||
| 3. Sprinklers spray the lettuce | |||
| 4. Lettuce is cut and packed in the field | |||
| 5. Boxes are trucked to the Colton Vale school kitchen | |||
| 6. Salad is served on the lunch tray |
Write two sentences below the chain.
Which link would you break first, and why did you choose that one?
From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.
Completed Exemplar
Pasture → Ditch → Sprinklers → Harvest → Delivery → Lunch tray
| Link | What happens here | How germs could reach the food | What breaks this link |
|---|---|---|---|
| 1. Rain falls on the pasture above Dowsett Ditch | Rain washes over ground where cattle graze and carries manure downhill into the ditch. | Manure carries bacteria that can make people sick, and the runoff puts them into the water supply for the field. | Fence the cattle back from the ditch and keep a strip of grass between the pasture and the water to catch runoff. |
| 2. Ditch water is pumped into the irrigation line | A pump draws ditch water into pipes that feed the field. | Whatever is in the ditch is now in the irrigation line, and the farm cannot see it. | Test the irrigation water before the season and again after big storms, and hold the water in a settling pond before use. |
| 3. Sprinklers spray the lettuce | Overhead sprinklers wet the whole plant, including the leaves. | Water sits on the exact part of the plant that people eat raw. | Switch to drip irrigation that wets the soil instead of the leaves, or stop overhead watering several days before harvest. |
| 4. Lettuce is cut and packed in the field | Workers cut heads by hand and place them in bins. | Hands, knives, and dirty bins can move germs from one head to many. | Put handwashing stations and clean restrooms in the field, sanitize bins and knives, and keep sick workers off the harvest crew. |
| 5. Boxes are trucked to the Colton Vale school kitchen | Boxes are loaded, driven, and stored until the kitchen needs them. | Warm boxes let any bacteria already present multiply during the trip. | Cool the lettuce quickly after harvest and keep it cold in the truck and in the kitchen cooler. |
| 6. Salad is served on the lunch tray | Kitchen staff rinse, cut, and serve the lettuce. | Cutting boards, hands, and nearby raw meat can add germs at the last moment. | Wash hands and produce, keep raw meat separate, keep salad cold on the line, and remember that rinsing lowers risk without removing everything. |
Two-sentence response, sample: I would break link 3 first, because switching to drip irrigation keeps the ditch water off the part of the plant we eat raw. It protects the lettuce even in a year when the buffer strip fails and the ditch test comes back bad.
Differentiation
Support
Give these students the chain with columns two and three already filled in, so their work is the control step and the closing sentences. Provide a word bank containing "buffer strip," "drip irrigation," "cold storage," "handwashing station," and "water testing," and let them place each term in the row where it fits.
Extension
Ask students to add a seventh link for a home kitchen and to explain why food safety rules put most of their weight on links 1 through 4 rather than on the later links. Have them rank all seven links by how many people one control step protects.
ELL supports
Pre-teach "runoff," "irrigation," and "harvest" with three photographs and a gesture for each. Provide the chain arrows as a strip of labeled pictures across the top of the page, and give the sentence frame: "I would break link ___ first because ___."
Extensions
Students can compare this chain against the path taken by a food they eat that is always cooked, such as rice or beans, and explain why the raw-eaten crop carries more risk from irrigation water. A school nutrition director or a produce buyer can be invited to describe what a school kitchen actually checks when a delivery arrives, including temperature records and the supplier's own water testing.