Biology 1a. Experimental Design

Front

The factor that we choose to change in an experiment.

Example: Changing the amount of sunlight plants get (one group 2 hours, another 6 hours).

Back

Independent Variable

Front

The group(s) that get the changed condition (the independent variable). Example: Students forced to take test with band playing instead of a quiet room.

Back

Experimental Group(s)

Front

The factor that is measured in an experiment, the data. Example: Plant height measured after 4 weeks.

Back

Dependent Variable

Front

The group that does not get the change; used for comparison. Example: Group that takes the test like normal.

Back

Control Group

Front

The factors in an experiment that we do the same each time. Example: Same soil, same water, same pot size for every plant.

Back

Controlled Variables

Front

A clear, testable guess about what will happen. Often written as an “If…, then…” sentence. Example: “If plants get more sunlight, then they will grow taller.”

Back

Hypothesis

Front

Simple uses: Line graph — shows change over time (e.g., plant height each week). Bar graph — compares groups (e.g., average height of each group). Pie chart — shows parts of a whole (e.g., percent of students choosing each favorite fruit).

Back

Graphs (line, bar, pie)

Front

Quantitative = numbers or measurements (e.g., 12 cm tall, 5 apples). Qualitative = descriptions or observations (e.g., leaves are green, plant looks healthy).

Back

Quantitative Data vs Qualitative Data

Front

A short way to explain results: Claim = answer to the question. Evidence = data that supports the claim. Reasoning = science explanation connecting evidence to the claim.

Back

CER (Claim, Evidence, Reasoning)

Front

Steps scientists use to investigate: Ask a question → Research → Make a hypothesis → Plan the experiment → Test (collect data) → Analyze results → Draw conclusion → Communicate results. Example: Using these steps to test how fertilizer affects plant growth.

Back

Scientific Method