Scientific method / Controlled variables / Dedicated lab room

Four matching seedlings, lamps, soil and measured water are labeled Keep the setup consistent, with light, water and soil held the same. — These seedlings share the same light, water and soil so those conditions do not explain differences in the measured result.

← RETURN TO LESSONLAB DOSSIER / GUIDED VIDEOENGLISH VOICEOVER · CAPTIONS

SCIENTIFIC METHOD · GRADES 4–8

Fair-test control room

INVESTIGATION QUESTIONWhat happens when a second condition changes too?

● ILLUSTRATIVE SCIENCE MODEL

ENGLISH CAPTIONS

Set lamp distance as independent factor and choose levels for comparison.

0.0 / 3.0 s

01 / SCIENCE

What explains the result?

If multiple conditions change together, a result cannot identify which one caused the difference.

02 / EVERYDAY CONNECTION

Where does this matter?

Fair tests support product comparisons, classroom investigations, and medical studies.

03 / MODEL LIMIT

What should you keep in mind?

Confidence is an instructional score, not a statistical probability or a substitute for repeated data.

Continue to the interactive experiment ↓

A row of identical beakers, balances, timers and rulers is labeled Use the same method, with tool, timing and procedure held constant. — Using the same tool, timing and procedure makes measurements more comparable across trials.

YOUR TASK

What happens when a second condition changes too?

Fair-test control room: experiment-specific laboratory scene

READ THE BENCH CARD

Hold the comparison conditions steady

Change lamp distance while keeping the other growing conditions matched across groups. Confidence is an instructional score, not a statistical probability or a substitute for repeated data.

MATERIALS / DATAMatched samples · Condition cards · Data log

TEST FACTOR · CHANGE THIS ONELamp distance30 cm

Compare plants under two or more distances. What must stay matched for a fair comparison?

Hold these setup details steady

Same bean varietySame water volumeSame pot sizeLamp distance

WHAT TO TAKE AWAY

If multiple conditions change together, a result cannot identify which one caused the difference.

WHERE THIS IS USED

Fair tests support product comparisons, classroom investigations, and medical studies.

MODEL LIMIT Confidence is an instructional score, not a statistical probability or a substitute for repeated data. The activities on this page do not store classroom measurements.