Science: Reading Data, Designing Experiments, and Using Evidence
GED Science passages present short texts, tables, graphs, and diagrams drawn from life science, physical science, Earth and space science, and health. Most questions test science practices rather than memorized facts: interpreting data, designing and evaluating investigations, reasoning with evidence, and understanding how scientific ideas connect. Know the vocabulary of experiments - hypothesis, independent variable (what the researcher changes), dependent variable (what is measured), control group, constants, sample size, and replication. Be comfortable with basic physical science ideas: states of matter, conservation of mass, force and motion, energy transfer, and the difference between physical and chemical changes. In life science, understand cells, heredity, natural selection, and ecosystems and energy flow. In Earth science, know the water cycle, rock types, plate tectonics, and how the Sun drives weather and climate.
Traps to watch
- Correlation vs. causation. A graph showing two trends together does not prove one causes the other.
- Confounded variables. If two things change at once, you cannot credit either one.
- Ignoring the control. Without a comparison group, results are weak evidence.
- Overreading a graph. Check axis labels and units before drawing a conclusion.
Worked example
A student waters plants with 50 mL, 100 mL, and 150 mL daily and measures height after two weeks. The independent variable is water volume; the dependent variable is plant height; constants include soil type, light, and pot size. Rule of thumb: change one variable at a time and keep everything else identical.