3.1 Science Data and Experiments
Key Takeaways
- GED Science rewards evidence handling more than memorized science facts: identify variables, controls, trends, and supported conclusions.
- The official Science test is 90 minutes with no break and includes reading, experiment design, and numbers-or-graphics tasks.
- The educator blueprint weights Science content at about 40% life science, 40% physical science, and 20% Earth and space science.
- A conclusion is strong only when the data directly supports it and obvious alternate explanations have been controlled or acknowledged.
- Read graph titles, units, axes, sample size, and direction of change before doing any calculation.
Science Is Evidence First
GED Science questions usually give you enough information to reason from the passage, table, diagram, or experiment. You still need core vocabulary, but the higher-yield skill is deciding what the evidence actually shows. The official subject page emphasizes scientific concepts, measurements, experimental setup, graphs, and data sets. Treat every item as a small evidence task.
The official test-subject page lists Science as a 90-minute test with no break. The topic groups are reading for meaning in science, designing and interpreting science experiments, and using numbers and graphics in science. Calculator access and a calculator reference sheet are available, so your attention should stay on setup, interpretation, units, and claims.
Experiment Setup
| Feature | What to Ask | GED Trap |
|---|---|---|
| Hypothesis | What prediction is being tested? | Choosing a vague opinion instead of a testable claim |
| Independent variable | What was changed on purpose? | Confusing the treatment with the measured result |
| Dependent variable | What outcome was measured? | Picking a constant because it appears in the procedure |
| Control group | What gives the baseline? | Ignoring the group with no treatment or standard treatment |
| Constants | What stayed the same across groups? | Treating every listed material as a variable |
| Sample size | How many trials or subjects were used? | Trusting a broad claim from too little data |
Use this process on experiment questions:
- Name the outcome before reading the answer choices.
- Circle or mentally tag the one condition that differs between groups.
- Check whether all other conditions are held constant.
- Compare the measured outcome against the control.
- Choose the conclusion that is no stronger than the evidence.
Reading Data Displays
Start with the title, axes, labels, and units. A line graph often shows change over time. A bar graph compares categories. A table may require sorting values, calculating a difference, or finding a rate. If the question asks for a trend, do not overfocus on one unusual point unless the item asks about that point.
For example, if a table shows plant growth at 0, 25, 50, and 75 grams of fertilizer, the best conclusion may be that growth increases up to a point. It would be too strong to claim fertilizer always improves growth unless the data includes enough levels and shows no limit. If the highest amount produces less growth, the better conclusion is that the relationship is not simply more-is-better.
Correlation, Causation, and Claims
Correlation means two measurements move together. Causation means one factor produces the change. GED Science often asks you to avoid causal claims when the situation is only observational. A graph showing that asthma visits and air pollution rise together suggests a relationship. A controlled study with comparable groups gives stronger support for a cause.
Strong conclusions use careful language: supported, suggests, consistent with, or likely under these conditions. Weak answers often say proved, always, never, or caused when the design does not justify that level of certainty. If a study lacks random assignment, lacks a control group, has a tiny sample, or changes two factors at once, mention the limitation.
Content Areas to Recognize
The educator guide organizes Science content into life science, physical science, and Earth and space science. Life science includes human body systems, cells, genetics, evolution, ecosystems, photosynthesis, and energy flow. Physical science includes matter, chemical reactions, force, motion, waves, electricity, heat, and conservation of energy. Earth and space science includes plate tectonics, Earth systems, weather, climate, resources, and astronomy.
You do not need to memorize a full textbook. You do need to connect vocabulary to evidence. Producers make food energy available in ecosystems. Net force explains changes in motion. Plate boundaries help explain earthquakes, volcanoes, and mountain building. Physical changes keep the same substance; chemical changes form new substances. These concepts matter because they help you interpret the passage faster.
Final Science Checklist
- Identify the variable changed on purpose and the result measured.
- Use the control group as the baseline comparison.
- Read units before calculating.
- Separate data-supported claims from guesses.
- Watch for correlation being overstated as causation.
- Prefer the answer that fits all the data, not just one point.
- Use supplied formulas and references instead of trying to memorize every equation.
On test day, slow down at the beginning of each science stimulus. A few seconds spent labeling variables and units usually saves more time than rushing into the choices.
A student tests whether a new plant light improves growth. Ten identical seedlings receive the new light for 8 hours per day, and ten identical seedlings receive a standard light for 8 hours per day. After three weeks, the student records each plant height. What is the dependent variable?
A graph shows that lake algae increased during the same months that fertilizer runoff increased. Which conclusion is best supported by this graph alone?