Worksheet Grade 4 Engineering & Design

Portwick Camp's Wash Station Drain Field: Checking Two Designs

A grade 4 worksheet checking two gravel drain field designs for a fictional camp wash station against a creek setback, a gravel depth rule, and a token limit.

Grade: Grade 4
Subject: Engineering & Design
Material: Worksheet
Time: 35 min
Prep: No prep
Materials: None

Standards

4.MD.A.1 Common Core Math

Know relative sizes of measurement units within one system of units including km, m, cm; kg, g; lb, oz; l, ml; hr, min, sec. Within a single system of measurement, express measurements in a larger unit in terms of a smaller unit. Record measurement equivalents in a two-column table.

How this material aligns: Item 7 expresses gallons in the smaller unit of quarts, while items 2 and 3 apply the same knowledge of relative unit size to read gravel depths given in inches as feet.

All materials for 4.MD.A.1 →

4.NBT.B.5 Common Core Math

Multiply a whole number of up to four digits by a one-digit whole number, and multiply two two-digit numbers, using strategies based on place value and the properties of operations. Illustrate and explain the calculation by using equations, rectangular arrays, and/or area models.

How this material aligns: Items 1, 5, 6 and 9 multiply a two-digit length or flow by a one-digit number to find total trench length, trench bottom area, and a week of use.

All materials for 4.NBT.B.5 →

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: Items 10 and 11 have students judge two drain field designs against the same three camp rules and propose a fix for the one that fails.

All materials for 3-5-ETS1-2 →

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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 convert inches to feet and gallons to quarts in a design check.
Students will multiply and subtract to compare two drain field designs.
Students will name the design that follows every camp rule and fix the one that does not.

Vocabulary

Key words: drain field, trench, gravel, setback, supply token

Teacher overview

The worksheet works through one situation from start to finish: a fictional camp is building an outdoor handwashing station, the rinse water has to go somewhere, and two gravel drain field designs are on the table. Items 1 through 9 are the arithmetic a crew would actually do, and items 10 and 11 turn those numbers into the decision. The misconception to expect sits in items 2 and 3, where fourth graders convert inches to feet by multiplying by 12 instead of dividing, because most of their practice runs the other direction. Placing those two conversions early means the error shows up in class while there is still time to catch it before item 10.

Portwick Camp's Wash Station Drain Field: Checking Two Designs — Grade 4 Engineering & Design

Name: ____________________________ Date: ______________

Student Worksheet

Portwick Camp is a fictional summer camp. The camp is building a new outdoor handwashing station near the dining hall. The rinse water will run into a gravel trench called a drain field. Water soaks down through the gravel and into the soil. The soil and the tiny living things in it clean the water as it sinks.

The camp wrote three rules for the drain field.

Rule 1: the trench must be at least 50 feet from Ferrowick Creek.
Rule 2: the gravel must be at least 12 inches deep.
Rule 3: the camp may spend no more than 40 supply tokens.

The builder drew two designs.

Design	Trenches	Length of each trench	Width	Gravel depth	Distance from the creek	Cost in supply tokens
Design 1	1 trench	20 feet	2 feet	12 inches	35 feet	28
Design 2	2 trenches	12 feet	2 feet	18 inches	60 feet	38

Design 2 has 2 trenches. Each one is 12 feet long. How many feet of trench is that in all?
Design 1 has gravel 12 inches deep. There are 12 inches in 1 foot. How many feet deep is that gravel?
Design 2 has gravel 18 inches deep. There are 12 inches in 1 foot. How many feet deep is that gravel?
Rule 1 says a trench must be at least 50 feet from the creek. Design 1 sits 35 feet from the creek. How many more feet from the creek would Design 1 have to move?
The Design 1 trench is 20 feet long and 2 feet wide. What is the area of its bottom?
Design 2 has 2 trenches. Each one is 12 feet long and 2 feet wide. What is the total area of both trench bottoms?
On a busy day the wash station uses 60 gallons of water. There are 4 quarts in 1 gallon. How many quarts is 60 gallons?
The camp has 40 supply tokens. Design 2 costs 38 supply tokens. How many supply tokens would be left?
The wash station uses 60 gallons on each busy day. How many gallons does it use in 7 busy days?
Which design follows all three camp rules?
The other design breaks one of the rules. Write one change the camp could make to that design so it follows the rule it breaks.

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: 24 feet.
2 trenches × 12 feet each = 24 feet of trench.
Answer: 1 foot.
12 inches ÷ 12 inches per foot = 1 foot. Dividing is the right move here, because feet are larger than inches, so the number gets smaller.
Answer: 1 1/2 feet.
18 ÷ 12 = 1 with 6 inches left over, and 6 inches is half a foot, so the depth is 1 1/2 feet. This is deeper than Rule 2 asks for, and a rule that says "at least" allows more.
Answer: 15 feet.
50 feet − 35 feet = 15 feet. Design 1 would have to sit 15 feet farther from Ferrowick Creek.
Answer: 40 square feet.
20 feet × 2 feet = 40 square feet of trench bottom.
Answer: 48 square feet.
One trench bottom is 12 feet × 2 feet = 24 square feet. Two of them is 24 × 2 = 48 square feet. Design 2 gives more soaking surface than Design 1.
Answer: 240 quarts.
60 gallons × 4 quarts per gallon = 240 quarts. Multiplying is right here, because quarts are smaller than gallons, so the number gets larger.
Answer: 2 supply tokens.
40 tokens − 38 tokens = 2 supply tokens left.
Answer: 420 gallons.
60 gallons × 7 days = 420 gallons in a week of busy days.
Answer: Design 2.
Design 2 sits 60 feet from the creek, which clears the 50-foot rule. Its gravel is 18 inches deep, which clears the 12-inch rule. It costs 38 supply tokens, which is not above the 40-token limit. Design 1 meets Rules 2 and 3 but sits only 35 feet from the creek, so it fails Rule 1.
Answer: Move the Design 1 trench at least 15 feet farther from the creek.
Accept any change that fixes the setback, such as shifting the whole trench uphill away from Ferrowick Creek, or moving the wash station itself to a spot where a 20-foot trench can sit 50 feet or more from the water. Do not accept a change that only makes the gravel deeper or the trench longer, because neither one moves the trench away from the creek.

Differentiation

Support

Give these students a drawn side view of one trench showing the gravel layer, the soil beneath, and a labeled arrow to the creek, so the three rules attach to parts of a picture. Provide a conversion card reading "inches to feet: divide by 12" and "gallons to quarts: multiply by 4" next to items 2, 3, and 7. For item 10, have them check one rule at a time and cross out a design as soon as it breaks a rule.

Extension

Ask these students to design a third layout that follows Rules 1 and 2 and gives at least as much bottom area as Design 2. They should state the number and length of their trenches, show the area calculation, and name the one thing they are least sure about, such as whether the ground is level enough that far from the dining hall.

ELL supports

Pre-teach trench, gravel, soak, setback, and at least with sketches, and show the difference between "at least 12 inches" and "exactly 12 inches" using two stacks of blocks. Allow number-only answers on items 1 through 9, and provide the frame "Design ____ follows all three rules because ____, ____, and ____." for item 10.

Extensions

Ask students what a camp would have to learn about its ground before building either design, such as how fast water soaks in after rain and how high the water sits underground in spring, and discuss why a drain field that works in August can back up in April. Then compare the camp's three rules with the reasons behind them, matching the creek setback to keeping the creek clean and the gravel depth to giving the water enough room to spread out.