Scientific method / Control vs experimental / Dedicated lab room

Matching seedling trays are labeled Baseline beside treatment, with only the experimental group receiving a treatment drop. — The control group provides a baseline. The experimental group receives the treatment being investigated.

← RETURN TO LESSONLAB DOSSIER / GUIDED VIDEOENGLISH VOICEOVER · CAPTIONS

SCIENTIFIC METHOD · GRADES 4–8

Find the right comparison group

INVESTIGATION QUESTIONHow does a baseline change interpretation of growth?

● ILLUSTRATIVE SCIENCE MODEL

ENGLISH CAPTIONS

Define fertilizer as treatment, keep the usual water schedule in both groups.

0.0 / 3.0 s

01 / SCIENCE

What explains the result?

A control provides a same-time baseline; a treated group differs by the intended treatment.

02 / EVERYDAY CONNECTION

Where does this matter?

Comparison groups help test fertilizers, learning approaches, and product changes.

03 / MODEL LIMIT

What should you keep in mind?

Too much fertilizer can harm plants; the example is a model and does not recommend dosing crops.

Continue to the interactive experiment ↓

Seedling samples are randomly sorted into blue and amber groups before only the amber group receives treatment. — Random assignment can reduce systematic differences between groups before the treatment begins.

YOUR TASK

How does a baseline change interpretation of growth?

Find the right comparison group: experiment-specific laboratory scene

READ THE BENCH CARD

Identify the untreated comparison group

Compare two otherwise similar plant groups and identify which one did not receive the treatment. Too much fertilizer can harm plants; the example is a model and does not recommend dosing crops.

MATERIALS / DATAMatched seedlings · Water measure · Growth chart

GROUP AUsual watering

No fertilizer added

Comparison group

GROUP BSame watering

Measured fertilizer added

Treatment group

Which group is the control?

WHAT TO TAKE AWAY

A control provides a same-time baseline; a treated group differs by the intended treatment.

WHERE THIS IS USED

Comparison groups help test fertilizers, learning approaches, and product changes.

MODEL LIMIT Too much fertilizer can harm plants; the example is a model and does not recommend dosing crops. The activities on this page do not store classroom measurements.

A comparison chart labeled Control Group and Experimental Group shows separate measurements for two seedling groups. — Compare the measured outcomes across groups while considering variation within each group.