Scientific Method, Measurements, and Experimental Variables

Vocabulary flashcards covering observation vs. inference, qualitative vs. quantitative data, accuracy and precision, experimental group setup, controlled constants, and independent vs. dependent variables.

Observation

Something that can be perceived or detected using the senses, such as sight, smell, or touch.

Inference

An educated conclusion or guess based on observations.

Qualitative Observation

An observation that describes qualities or characteristics without numbers, such as color, texture, or size (e.g., 'the frog is bright green').

Quantitative Observation

An observation that involves numbers or specific measurements (e.g., 'the frog is $6\,\text{cm}$ long' or 'the beaker holds $250\,\text{mL}$ of water').

Precision

How consistent measurements or data points are with each other.

Accuracy

How close a measurement is to the true, correct, or accepted value.

Systematic Measurement Error

An error caused by a flawed instrument, such as a thermometer that consistently reads too low (e.g., Student 1 measuring boiling water at $92.0\,\text{°C}$ to $92.2\,\text{°C}$ instead of $100\,\text{°C}$).

Independent Variable (IV)

The variable in an experiment that is deliberately changed or manipulated by the experimenter; it is plotted on the x-axis of a graph.

Dependent Variable (DV)

The variable that is measured or observed to determine the effect of the independent variable; it is plotted on the y-axis of a graph because its outcome depends on the independent variable.

Experimental Group

The group in an experiment that receives the variable or condition being tested (e.g., bean plants grown under red light).

Control Group

The group in an experiment that receives no experimental treatment and serves as a baseline for comparison (e.g., bean plants grown in natural sunlight or mice given no vitamin).

Hypothesis

A testable prediction written in an 'If…, then…' format describing the expected cause and effect of an experiment.

Controlled Variables (Constants)

Conditions in an experiment that must be kept identical across all groups, such as the soil type and environment, to ensure only one variable is being tested.

Repeated Trials

Performing an experiment multiple times to ensure results are consistent and not based on a single freak accident or outlier data point.

Uncontrolled Variable Problem

Failing to keep all variables constant—such as changing plant species (bean vs. tomato) in addition to light type—which invalidates the experiment because different species grow at different initial rates.

Fertilizer Experiment Variables

An experiment where the IV is fertilizer added to soil, the DV is the amount of tomatoes produced, and the control group is tomato plants receiving no fertilizer.

Mouse Vitamin Experiment Variables

An experiment where the IV is the vitamin given, the DV is how fast the mice run through a maze, and the control group is mice given no vitamin.

Salt Water Boiling Experiment Variables

An experiment testing salt amounts ($0\,\text{g}$, $5\,\text{g}$, or $10\,\text{g}$) as the IV against the time water takes to boil as the DV, where water with $0\,\text{g}$ salt is the control group.

Water Volume vs. Plant Growth Experiment

An experiment testing daily water ($0\,\text{mL}$ to $50\,\text{mL}$) on the x-axis (IV) to measure average plant height in $\text{cm}$ on the y-axis (DV) after 3 weeks across 5 plants per treatment level.