18.1 Scientific Inquiry in Science Instruction

Experimental vs. Nonexperimental Inquiry

TExES 116 expects teachers to plan both kinds of inquiry. They are not a hierarchy — one is not 'better' than the other. The choice depends on the question.

A common TExES distractor is treating 'descriptive' or 'field' research as not really science. The competency text explicitly lists both. A class that maps and counts monarch caterpillars on milkweed across three schoolyard sites over six weeks is doing nonexperimental inquiry — pattern-finding, not cause-testing — and it is fully legitimate.

Focusing Inquiry on Student-Relevant Questions

Inquiry is most powerful when the question is genuinely the students'. Strategies to help students generate, refine, and focus questions and hypotheses:

• 'I wonder' board: a running public list of questions students pose during a phenomenon or demonstration; the class later selects which to pursue.
• Question starters: 'How does ____ affect ____?' and 'What is the relationship between ____ and ____?' scaffold testable questions without supplying the content.
• Refining loops: a student's first question ('Why do plants grow?') is broad; the teacher prompts 'Which variable could we change in our terrariums?' until the question narrows to 'How does the amount of water affect bean plant height over 14 days?'
• Hypothesis frames: 'If ____ (manipulated variable) increases, then ____ (responding variable) will ____ because ____ (rationale).' The 'because' clause forces students to ground the hypothesis in a scientific idea, not a guess.

Safe and Proper Use of Grade-Appropriate Tools

Before any data collection, teach tool use explicitly. Grade-appropriate examples:

• Grades 4-5: hand lenses, thermometers, graduated cylinders, pan balances, rulers; introduce the digital probe as an extension of the thermometer.
• Grades 6-7: compound microscopes, data loggers with temperature and pH probes, digital scales; teach calibration and units.
• Grade 8: multimeters for circuits, light sensors for photosynthesis, spreadsheets for graphing and statistical comparison.

Safety instruction is non-negotiable: goggles for any pour, heat, or splash risk; closed-toe shoes; labeled chemical handling; proper electrical-battery practices; and explicit 'never taste, never smell directly' rules. Texas classrooms also follow district chemical inventories and the state-required safety acknowledgement.

Guiding Systematic Observations and Measurements

Students tend to observe what they expect to see. Teachers make observation systematic by structuring it: a data table designed before data collection forces students to decide what to measure and in what units. A reproducibility check (repeat a measurement three times and report the range) teaches that observation is not a single impression. A quadrat or transect makes field observation quantifiable rather than anecdotal — a class that 'just walks around' the schoolyard will overcount conspicuous species and miss others.

Critical Thinking, Logical Reasoning, and Evidence-Based Conclusions

TExES 022 asks teachers to promote 'critical-thinking skills, logical reasoning and scientific problem solving to reach conclusions based on evidence.' Three habits build these:

1. Distinguish evidence from opinion. A student claim that 'fertilizer makes plants taller' must be supported by measured heights, not the student's belief.
2. Distinguish correlation from causation. Two variables that change together may or may not be causally linked; a controlled experiment is the test.
3. Identify the alternative explanation. Ask 'What else could explain this?' before accepting a conclusion.

Multiple Explanations for One Result

A core inquiry practice is asking students to develop, analyze, and evaluate more than one explanation for the same data. If a class finds that plants in the sun grew more than plants in the shade, at least three explanations are worth considering: light drove photosynthesis (the expected explanation); the sunny plants also received more water inadvertently; the sunny plants were a different seed batch. Having students explicitly rank explanations by how well they fit all the evidence is a higher-order thinking move than simply stating the textbook answer.

Teaching Students to Identify Sources of Error

Students must be taught to identify and describe potential sources of error, distinguishing three categories:

• Random error affects precision (scatter around a true value); reduced by repeated trials and averaging.
• Systematic error affects accuracy (consistent offset); identified by calibration against a known standard.
• Procedural mistake affects validity (a confound that undermines the comparison); often requires redesign.

A class measuring bean growth that used different soil volumes in each pot has a procedural mistake, not 'random error.' Calling it random error hides a design flaw the student should fix.

Communicating and Defending Results: The CER Framework

The Claims-Evidence-Reasoning (CER) framework is the standard scaffold for student communication of inquiry results:

• Claim: a one-sentence answer to the investigation question ('Bean plants in full sun grew taller than bean plants in shade over 14 days.').
• Evidence: the relevant data, presented with units and trials ('Mean height: sun 18.2 cm, shade 11.4 cm; n = 10 per condition; range 16-21 cm vs. 9-13 cm.').
• Reasoning: the scientific principle that connects evidence to claim ('Photosynthesis requires light energy; more light enables more glucose production and thus more growth.').

A strong CER response also addresses counter-evidence and alternative explanations. Science notebooks are the day-to-day home for CER writing; structured oral presentations and gallery walks let students defend their reasoning to peers. Defense matters because the act of justifying forces students to evaluate their own evidence — a metacognitive move that deepens learning.