Cafeteria Waste Audit: Percent, Recycling and Diversion

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Science · Environmental Science / Earth Science
SP-ENVS-007 · Free to print and use in your classroom · substituteplans.com
Page 2
Cafeteria Waste Audit: Percent, Recycling and
Diversion
Science · Environmental Science / Earth Science · Grades 9-11 · 45 minutes
Time needed
45 minutes (one class period)
Prep
Copy the 2-page worksheet (one per student).
Technology
None. Calculators are strongly recommended.
Student
independence
High. Students work alone with the data table.
Copies to make
One 2-page worksheet per student
Materials
Pencils, Worksheet, Calculators
Goal for today: Students will calculate percentages and rates from waste audit data and will propose a plan that
reduces waste going to a landfill.
Before the bell
☐ Copy the worksheet, one per student (2 pages).
☐ Write on the board: Percent = part ÷ total × 100.
☐ Keep the answer key on your desk. Students should not touch any actual trash; the lesson uses a sample
data table only.
Say this to start
Good morning! Today’s science lesson is about waste. Students will study a sample table showing what a school
cafeteria threw away in one day, and calculate what percent each type makes up. Then they will make a plan to waste
less. This is a math and thinking lesson, and no one handles any real trash. The formula is on the board.
Run of show
Minutes
What you do
What students do
0–5
Take attendance. Hand out the worksheet. Read the title
and directions aloud.
Look over the worksheet.
5–10
Tell students to read the introduction and study the data
table. Read the percent formula on the board.
Read and underline the key terms.
10–30
Tell students to complete questions 1–9. Walk around and
remind them to show their math.
Calculate total weight, percentages, rates
and yearly totals.
30–38
Tell students to answer questions 10–11, the
multiple-choice questions.
Answer using the reading and the data.
38–45
Tell students to write their plan (question 12). Collect all
worksheets.
Write a plan with at least two actions, then
hand in the worksheet.
If things go wrong
• If a student asks if the numbers are real, tell them they are made-up sample numbers to practice the math.

SubstitutePlans.com
Science · Environmental Science / Earth Science
SP-ENVS-007 · Free to print and use in your classroom · substituteplans.com
Page 3
• If students get rounding differences, accept answers within 0.1 of the key when rounding to one decimal
place.
• If a student has trouble with the percent formula, give an example: 30 out of 120 is 30 ÷ 120 = 0.25, which is
25%.
• If students finish early, check that question 12 has at least two actions, then use the early finisher list.
Early finishers
• Design a one-page poster idea that tells students how to sort their lunch trash. Sketch it on the back.
• List three ways a family can reduce food waste at home.
Support and challenge
• Support: Let students use calculators and complete questions 1–5 and 10–12.
• Challenge: Ask students to calculate the percent of the day’s waste that would remain for the landfill if only
half of the food waste were composted and all recyclables were recycled.
Notes for the teacher (you fill this in)
Jot a few lines before you leave. A full Daily Sub Report is in the free Sub Survival Kit at SubstitutePlans.com.
How far the class got / what to pick up next:
Students who were especially helpful:
Anything the teacher should know: