TEAS scientific reasoning practice: variables and evidence
Short answer: Identify what the researcher changes, what is measured, and what else could explain the result. Then choose the conclusion that the stated evidence supports. A larger observed value alone does not establish cause and effect.
You recognize the science vocabulary. Can you spot the flaw in the experiment? These original practice items focus on interpreting a study, a skill included in the ATI TEAS science outline. They are educational examples, not released ATI questions or a score predictor.
Attempt each question before opening its explanation. The numbers below are invented teaching data, not research findings.
A repeatable way to read an experiment
- Change: identify the deliberately manipulated factor, the independent variable.
- Measure: identify the recorded outcome, the dependent variable.
- Compare: check what stays constant and whether another difference could explain the outcome.
- Conclude: stay within the comparison actually tested. Observational association alone does not establish causation.
This method follows the distinction between experimental and observational evidence described by OpenStax Psychology. It is a reading strategy, not a claim that every study has a single independent variable.
Original practice with worked answers
Practice 1
A student randomly assigns identical sugar cubes to water held at different temperatures. Each beaker contains the same water volume and uses the same stirring procedure. The student records the time until each cube fully dissolves. What is the dependent variable?
- Water temperature
- Time until the cube fully dissolves
- Water volume
- Stirring procedure
Reveal answer and reasoning
Answer: B. B is the measured outcome. Temperature is deliberately varied, so A is the independent variable. Water volume and stirring procedure are held constant in the stated design; C and D are controls, not the recorded outcome.
Practice 2
To compare fertilizer A with fertilizer B, a student gives plants receiving A 40 mL of water daily and plants receiving B 80 mL daily. All other stated conditions are matched. Which change most directly removes the described confound?
- Measure plant height more frequently
- Use the same daily water amount in both groups
- Rename the fertilizer groups
- End the experiment as soon as a difference appears
Reveal answer and reasoning
Answer: B. B removes the water difference that varies along with fertilizer type. A adds observations but leaves the unequal watering. C changes only a label. D can introduce a stopping bias and still does not isolate fertilizer type. Matching water would address this stated flaw; it would not prove that every other design issue is solved.
Practice 3
In a fictional dissolving experiment, three trial times at 20 °C are 90, 94 and 92 seconds. At 40 °C they are 52, 56 and 54 seconds. Cube size, water volume and stirring are matched. Which statement describes these observations without going beyond them?
- Every substance dissolves faster whenever temperature rises
- The mean time is lower at 40 °C in these trials
- The cubes at 40 °C have a mean time of 92 seconds
- Temperature has no possible relationship to dissolving time
Reveal answer and reasoning
Answer: B. B matches the observations: (90 + 94 + 92) / 3 = 92 seconds; (52 + 56 + 54) / 3 = 54 seconds. The observed mean is 38 seconds lower at 40 °C. A generalizes beyond the substance and conditions tested. C swaps the group means. D dismisses a possible relationship despite the observed difference. These means alone do not establish statistical significance or a universal law.
Practice 4
A survey finds that students who report more practice sessions also report higher science scores. The researchers did not assign practice schedules or measure prior science knowledge. Which conclusion is best supported?
- Extra sessions caused every score increase
- Prior knowledge cannot affect the result
- Practice frequency and score are associated in this sample
- The survey proves a particular study product works
Reveal answer and reasoning
Answer: C. C describes the observed association. Students may differ in prior knowledge, motivation or other factors, so A and D make unsupported causal claims. B rules out an unmeasured factor without evidence. A survey can suggest a question for further study without establishing which factor caused the result.
Turn the mistake into your next practice task
If you missed a variables question, label the change and measurement before looking at the options. If you missed the data question, compute each group separately and check the conclusion for words such as “every” or “proves.” Then try a different question rather than memorizing this answer letter.
Continue with membrane transport and osmosis explanations, or see the TEAS practice scope. For saved account practice and AI-tutor access, review the current access options. Use the tutor to unpack a step, then check it against the worked explanation and source; AI responses can make mistakes.
Sources and scope
Source check: September 11, 2026. Exam scope is based on the test maker’s outline. Definitions are linked separately; examples and worked calculations are original.
Frequently asked questions
Is a control variable the same as a control group?
No. A control variable is a condition kept consistent for a comparison. A control group is a comparison group, such as a group without the tested treatment. Read the study design before deciding which term applies.
Are these actual TEAS questions?
No. These are original single-answer educational items. They are not released exam items, do not reproduce every official item format and do not predict an official score.
Does repeating an experiment fix confounding?
Repeating the same confounded design does not remove the confound. Address the alternative explanation in the design, then use repeated observations to assess consistency.
Reading is good. Answering is better.
Read original worked examples and try free practice questions. Account practice adds saved progress, missed-question review and an AI tutor; check the access options before buying.
AdmitNurse is an independent practice service and is not affiliated with, sponsored by or endorsed by ATI, Elsevier or any nursing school. Practice items are original and are not actual exam questions. Confirm current exam details with the test maker and current admission requirements with your nursing program.