Whole Earth Curriculum WEC

Lesson 03 — A Controlled Experiment

Learners put the pieces together. They plan and run one controlled experiment — does a covered cup keep water warmer than an open one? — changing only one thing (the cover) and keeping the rest the same. They measure with a thermometer and units, repeat the test across three trials, compare the results, and write what the evidence shows. This is the full shape of an honest test: change one thing, keep the rest the same, measure, and repeat.

D06 P3: Intellectual & Cognitive Awareness D06.S1 60 minutes Draft

Objectives

Essential question

How do measurement, fair-testing, and repeated trials come together in one trustworthy experiment?

controlled experimentfair testvariablekeep the samemeasureunitrepeated trialsevidence

Materials

Standard materials

Low-tech / no-cost

Enriched / lab & device

Works in different contexts

Two cups side by side — one covered and one open — labeled what changes, with the same water, cups, and time labeled what stays the same, plus a small results table of three repeated trials
Two cups side by side — one covered and one open — labeled what changes, with the same water, cups, and time labeled what stays the same, plus a small results table of three repeated trials

Lesson 3 — A Controlled Experiment

Summary

Grade 3 introduced the fair test — change one thing, keep the rest the same. Lessons 1 and 2 added measurement (numbers with units) and repeated trials. Now the three join into a controlled experiment: learners ask “Does a covered cup keep water warmer than an open one?”, change only one thing (the cover), keep the cups, water, place, and time the same, measure with a thermometer across three repeated trials, and write what the evidence shows. This is the honest shape of every trustworthy test.

Objectives

  • Use simple tools to measure and record observations with units. (D06.S1.04.01)
  • Compare results across repeated trials and explain why repeating a test matters. (D06.S1.04.02)

Connection

When a cook tries a new recipe, they do not change the salt, the heat, and the pan all at once — they would never know what worked. They change one thing, taste, and try again. When a bike rider wants to know if oiling the chain makes the ride easier, they oil only the chain and keep the tires, the road, and the rider the same. That is a controlled experiment: change one thing, keep everything else the same, measure the result with a unit, and repeat it to be sure. It is the same careful habit in a kitchen, a workshop, or a science lab — and it is how we come to trust what we learn.

Materials

  • Two identical cups and a thermometer
  • Warm water (facilitator only — not boiling)
  • A timer or clock
  • A class experiment chart

Preparation

  • Pour the same amount of warm water into two identical cups; cover one, leave one open.
  • Set out the thermometer and timer.
  • Prepare the chart with What changes | What stays the same | Trial 1 | Trial 2 | Trial 3.

Facilitator note

This lesson is written to the learner (“you”). It is the capstone of the inquiry strand, so structure it as a worked example then guided practice (Kirschner, Sweller & Clark, 2006): plan the test together on the chart first, naming the one change and the things kept the same, then run the trials as a group, and let learners write their own conclusion. Handle warm water safely yourself — never boiling, and never left where a learner could spill it on skin. Keep the egalitarian lens alive: a controlled experiment belongs to everyone, not only to people in labs; anyone with two cups and a hand can ask this question and get real evidence. Remind learners that a result that surprises us is still evidence — we describe it honestly and wonder why. This experiment feeds forward: learners will reuse “change one thing, keep the rest the same” all year.

Procedure

  1. Gather and remember (5 min). You have measured with tools and units, and you have repeated a test three times. Today you will do both at once in a controlled experiment.
  2. Plan the test (10 min). Our question: does a covered cup keep water warmer than an open one? Say the one thing that changes (the cover) and everything we keep the same (the cups, the amount of water, the place, the time). Predict: which cup will stay warmer, and why?
  3. Run it with repeated trials (20 min). After the same time, measure the temperature of each cup with the thermometer — say the number and its unit (degrees Celsius) — and record it. Pour fresh warm water and run it again (Trial 2), then again (Trial 3). Compare the three trials.
  4. Read the evidence (15 min). Which cup stayed warmer, and was that true across all three trials? Were the trials close together? Write a sentence: “The evidence shows that ___ because ___.”
  5. Close (5 min). A controlled experiment changes one thing, keeps the rest the same, measures with units, and repeats. That is how we build trust in what we know.

Differentiation

  • Support: Use a picture board for “change” and “keep the same,” and record with a partner’s help.
  • Support (non-speaking): Point to the cup that stayed warmer and to the cover as the one change.
  • Support (blind/low-vision): Feel both cups with the back of the hand and describe which is warmer; a partner reads the thermometer aloud.
  • Extension: Write a new testable question, list the one change and three things kept the same, and run two trials.

Assessment

  • Formative (observation): Can the learner name the one thing that changed and at least two things kept the same?
  • Performance: The learner runs or helps run three trials and records each with a unit.
  • Artifact (portfolio): The completed experiment chart with a written conclusion, kept for the unit portfolio.

Home connection

At home, run a tiny controlled experiment with a grown-up: “Which dries faster — a sock in the sun or a sock in the shade?” Change only the place, keep the socks, the water, and the time the same, and check twice.

Resources