Sandwich, Salad, or Soup? | CER Class Vote
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CER Class Challenge

Sandwich, Salad, or Soup?

Make a claim. Use evidence. Explain your reasoning. Then test whether your rule still works on the next food.

Three choices only.

1
Vote

Every food must be classified as a sandwich, salad, or soup.

2
Defend

Use specific characteristics as evidence.

3
Reason

Explain why that evidence fits your criterion.

4
Revise

If your rule breaks on a later example, improve the rule instead of forcing the food to fit.

Before you begin

How the class vote works

For each food, the teacher records the number of students voting for each category. The goal is not to guess the teacher's answer. The goal is to build a criterion, use evidence, and see whether the same criterion survives the next example.

Claim

“I classify this as a sandwich.”

Evidence

“It has a filling held by a starch on the outside.”

Reasoning

“That characteristic matches the criterion I am using for a sandwich.”

Challenge

“Would that same rule also classify a taco, sushi, or quesadilla? If not, should the rule change?”

A strong argument uses a criterion consistently. What happens when new evidence makes that criterion harder to defend?
Class data

How did we classify the foods?

Look for consensus, disagreement, and places where a rule that worked earlier stopped working.

SandwichSaladSoup
From food arguments to science

What happened to our criteria?

Where did we agree?

Which foods produced a clear consensus? What evidence made those claims easier to support?

Where did we disagree?

Was the disagreement about the observations, the definition, or how the evidence was interpreted?

Which rule survived?

Which criterion worked across the largest number of foods without special exceptions?

When did we revise?

Which food forced you to change your original rule? What new evidence made revision reasonable?

Science works the same way: claims and explanations should change when new evidence exposes a weakness in the rule or model we were using.

Teacher Notes

Purpose

Use a familiar, low-stakes classification problem to introduce CER as a way of making and defending conclusions from evidence. The rigor comes from asking students to test whether one criterion still works as the examples become increasingly ambiguous.

How to run the vote

  • Students must choose only Sandwich, Salad, or Soup.
  • Record votes with the + and − buttons or type totals directly.
  • Do not reveal a “correct” answer. Ask students to defend the criterion they used.
  • After each new food, ask whether the rule used on the previous food still works.
  • When a rule fails, invite students to revise it. Treat revision as stronger reasoning, not as losing an argument.
  • Votes are saved automatically in this browser until you reset them.

Round structure

  • Round 1: Make a claim. Hot Dog, Pizza, Taco.
  • Round 2: Test your rule. Quesadilla, Cereal with Milk, Chili.
  • Round 3: Defend or revise. Nachos, Sushi, Loaded Baked Potato.

Core prompts

  • What is your claim?
  • What specific evidence supports it?
  • What criterion are you using?
  • Why does that evidence satisfy the criterion?
  • Would the same criterion work for the previous food?
  • What evidence might someone use to disagree?
  • Do you need to revise your criterion?

Key debrief idea

Students can use the same observations yet reach different conclusions because their criteria differ. Evidence matters, but reasoning explains why the evidence satisfies a criterion. A stronger criterion works consistently across cases and is revised when new evidence exposes a weakness.