What makes a question investigable?
An investigable question can be answered with safe observations or measurements using available time, equipment and materials. A useful frame is: How does [variable changed] affect [variable measured] when [important controls] stay the same?
Patterns and relationships
A pattern describes how observations repeat or change across time, place or categories. A relationship asks how two measured variables vary together. A relationship in observational data is an association; it does not by itself prove that one variable caused the other.
Match question, method and data
Every named comparison must be tested and every claimed outcome must be measured. A method comparing pure and soapy water cannot answer a question about an untested liquid. A table of germination counts cannot answer a question about unrecorded seedling height.
Make vague words measurable
Replace words such as better, stronger, warmer or healthier with an operational measure: maximum load, force, temperature change or growth over a stated time. Include quantities and units when they make the test reproducible.
Reasoned predictions
Use: If [change], then [expected direction], because [relevant evidence or scientific mechanism]. The reason must explain the expected link rather than repeat the “then” clause. Predictions are written before results and may be revised when evidence disagrees.
Fair comparisons and confounding
Changing one target factor while keeping other influential conditions constant helps isolate a relationship. If two factors change together, the outcome is confounded: evidence cannot show which factor mattered.
Safety, ethics and feasibility
A measurable question may still be unsuitable if it risks harm, disturbs wildlife, requires an unrealistic timescale or exceeds available instruments. Redesign the question or use safe existing data rather than forcing a test.
Limits and careful claims
Instrument resolution, narrow ranges, small samples and missing comparison groups restrict what evidence can show. Predict cautiously beyond tested conditions and never turn an association into a causal claim without a design that isolates cause.
Important questions and answers
Q: Must an investigable question avoid yes/no wording? A: No; evidence and measurement matter more than grammar. Q: Must a prediction be correct? A: No; it must be justified before testing. Q: Can every scientific question be tested in class? A: No; safety, ethics, scale and equipment impose limits.
Assessment and mastery
Name the changed and measured variables, check that materials and data match the question, identify unavailable comparisons or confounders precisely, and justify predictions with an evidence-based mechanism. State what the evidence cannot establish.