DoAssignment study guide

A1.1 · Form research questions, predictions, and testable hypotheses

Learn to form research questions, predictions, and testable hypotheses through clear examples and targeted practice.

Ontario Grade 12 Biology

Scientific Investigation Skills and Career Exploration

Ontario Grade 12 Biology, expectation A1.1

A question such as “Do plants need light?” is a useful starting point, but it is too broad to guide a clear investigation. Which plants? How much light? What will count as growth? A strong research question narrows the topic. A hypothesis proposes a possible answer that can be tested. A prediction states what you expect to observe if the hypothesis is supported. This lesson builds those skills using familiar biology examples. It focuses on forming questions, predictions, and testable hypotheses—not on carrying out a full investigation or claiming that a proposed explanation is already true.

What you will learn

Distinguish a research question, a prediction, and a testable hypothesis.
Turn a broad biological topic into a focused question that can be investigated.
Identify the variables and measurements needed to make a hypothesis testable.
Write a prediction that follows from a hypothesis and can be checked with evidence.
Recognize limits in what an investigation can conclude.

1. Bridge from SBI3U: begin with a biological observation

In earlier biology courses, you studied living things at different levels. You may have connected an inherited trait to differences among individuals, linked an organ’s structure to its function, or asked how organisms interact with their environment. These topics can all prompt research questions. The key is to move from a broad interest to something specific that evidence could address.

Imagine that seedlings near a bright window seem taller than seedlings farther away. This is an observation: a description of what was noticed. It does not yet show that light caused the difference. The seedlings may also differ in water, soil, age, or other conditions. Treating an observation as a starting point helps keep a question open rather than assuming its answer.

A research question identifies what the investigation will examine. A focused question names the organism or system, the factor being considered, and the outcome to be measured. For example, “How does daily light exposure affect the height of bean seedlings over two weeks?” is more useful than “Do plants need light?” It can guide choices about what to vary and what to measure.

An observation can suggest a question but does not prove a cause.
A focused research question names a biological system, a factor, and a measurable outcome.
Use wording that leaves room for more than one possible result.

2. Separate the question, hypothesis, and prediction

A hypothesis is a proposed, testable explanation or answer to a research question. It should make a clear link between a factor and an outcome. A prediction is a specific statement about the result expected if the hypothesis is supported. The research question asks what will be investigated; the hypothesis gives a proposed answer; the prediction says what pattern should be observed.

For the seedling example, the question asks how daily light exposure relates to height after two weeks. A possible hypothesis is: “If bean seedlings receive more hours of light each day, then they will be taller after two weeks, because light exposure supports their growth.” The “because” clause gives a biological reason for the proposed relationship. It remains an explanation to test, not an established conclusion about these seedlings.

A matching prediction could be: “Bean seedlings receiving eight hours of light each day will have a greater average height after two weeks than seedlings receiving four hours, when other growing conditions are kept the same.” This identifies a comparison and an outcome. A prediction should follow from the hypothesis, but it is not the hypothesis itself.

The factor deliberately changed is the independent variable. The outcome measured is the dependent variable. These terms help make a question and hypothesis precise. Here, daily light exposure is the independent variable, and seedling height after two weeks is the dependent variable. Keeping other growing conditions similar helps make the comparison more informative.

A hypothesis proposes an answer that can be checked with evidence.
A prediction states the expected observation if the hypothesis is supported.
Name the factor changed and the outcome measured.
A biological reason can make the hypothesis clearer, but it does not make it true.

3. Make the idea testable and interpret evidence carefully

A testable hypothesis points to observations or measurements that could support it or fail to support it. “Plants grow better with good conditions” is not testable as written. “Good conditions” and “better” are unclear. The reader cannot tell what to change, what to measure, or what result would count as a difference.

Define how each key term will be measured. This is an operational definition: a precise description of how a factor or outcome will be set or recorded. For example, “daily light exposure” might mean the number of hours each seedling is placed under the same lamp each day. “Height” might mean the distance in centimetres from the soil surface to the tip of the main shoot, measured on day fourteen. Clear definitions help different people understand the same question in the same way.

A useful question also has a scope that can be investigated with available time and materials. It should identify a manageable group or system and a reasonable measurement. A question about every plant species in every habitat is too broad for a small class investigation. A question about one kind of seedling under a defined set of conditions is more focused.

Planning a testable question includes noticing other factors that could affect the outcome. In the seedling example, water, soil, container size, and starting age could matter. If they differ between groups, it may be hard to tell whether light exposure relates to the measured height. This is why a prediction often states that other conditions will be kept similar. It does not guarantee that every influence has been removed.

Evidence can support a hypothesis without proving it universally. A result from one small investigation may apply only to the organisms and conditions studied. If results do not match a prediction, that is still useful evidence: the hypothesis may need revision, or the investigation may have limitations. State what the evidence shows and avoid claiming more than the investigation could establish.

Replace vague words with defined factors and measurable outcomes.
An operational definition explains exactly how a factor is set or an outcome is recorded.
Consider other factors that could affect the measured outcome.
Evidence can support or fail to support a hypothesis; it does not automatically prove a universal rule.

4. A practical structure for drafting

Start with an observation or biological topic. Turn it into a question by naming the system, factor, and outcome. Next, propose a hypothesis that gives a possible relationship and, when appropriate, a biological reason. Then write a prediction with a defined comparison and a measurable result.

Before accepting the draft, check whether someone could tell what evidence to collect. Ask: Is the organism or system clear? Is the factor identifiable? Is the outcome measurable? Are important words defined? Does the prediction follow from the hypothesis? If the answer to any of these is no, revise the wording.

This structure is a planning aid, not a guarantee of a perfect investigation. A well-formed hypothesis can still be difficult to test with available resources. A question may also need narrowing to avoid an unfair or unclear comparison. The aim at this stage is to make the proposed investigation understandable and testable.

Draft in the order: question, hypothesis, prediction.
Make the prediction specific enough that possible outcomes can be compared.
Review clarity and measurability before using the draft to guide an investigation.

Worked example

Narrowing a question about pill bugs

A student notices pill bugs under damp leaves and wonders whether moisture affects where they are found. Form a focused research question, a testable hypothesis, and a prediction.

Focus the question
Name the organism, the factor, and the behaviour to record. A suitable question is: “How does substrate moisture affect the number of pill bugs found in each area after ten minutes?” The phrase “substrate moisture” refers to how damp the material under the pill bugs is.
Propose a hypothesis
State a possible relationship that could be checked. For example: “Pill bugs will be found more often in the moister area because they tend to occupy damp places.” This is a proposed explanation, not a conclusion established by the observation.
Write the prediction
Specify the expected comparison: “After ten minutes, more pill bugs will be counted in the damp substrate area than in the drier area.” Counting individuals makes the outcome observable. The setup would need clear moisture conditions and other conditions kept similar for the comparison to be useful.

Answer: Question: How does substrate moisture affect the number of pill bugs found in each area after ten minutes? Hypothesis: Pill bugs will be found more often in moister substrate because they tend to occupy damp places. Prediction: More pill bugs will be counted in the damp area than in the drier area after ten minutes.

Check: The question asks what will be investigated, the hypothesis proposes a reasoned relationship, and the prediction states a countable expected result.

Worked example

Defining a measurable outcome

A student asks, “Does exercise affect heart rate?” Revise the question and form a hypothesis and prediction that specify a measurable comparison.

Define the scope
The original question leaves “exercise” and “affect” unclear. A narrower question could ask: “How does a two-minute period of step-ups relate to the heart rate of participating students, measured immediately before and after the activity?” Heart rate means the number of heartbeats counted in one minute.
State a hypothesis
A testable hypothesis could be: “A two-minute period of step-ups will be followed by a higher heart rate than the resting measurement in participating students.” It links a defined activity to a measurable outcome without claiming the same response for everyone.
Make a matching prediction
The prediction is: “For each participating student, the heart rate measured immediately after the step-ups will be higher than the heart rate measured immediately before them.” This states the expected direction and comparison. The example is about forming a question and prediction, not medical guidance or a claim about any individual’s health.

Answer: Question: How does a two-minute period of step-ups relate to participating students’ heart rates measured immediately before and after? Hypothesis: The activity will be followed by a higher heart rate than the resting measurement. Prediction: The immediate post-activity measurement will be higher than the pre-activity measurement.

Check: The time points and outcome are defined. The prediction can be compared with measurements, while the wording stays limited to the participating students and conditions.

Worked example

Improving an inheritance question

A student asks, “Do inherited traits affect plant growth?” Improve the question and write a testable hypothesis and prediction without claiming that a particular genetic mechanism has been proven.

Choose a defined trait and outcome
The broad wording does not identify a trait, plant group, or measure of growth. Suppose two groups of the same plant species are already known to differ in leaf-colour trait. A focused question is: “Is the average height after three weeks different between the two leaf-colour groups when they are grown under the same conditions?”
Propose a cautious hypothesis
A testable hypothesis is: “The two leaf-colour groups will differ in average height after three weeks under the same growing conditions.” This proposes an association between the groups and the measured outcome. It does not claim that leaf colour itself causes a height difference or identify a specific gene.
Predict an observable result
A prediction could be: “After three weeks, the recorded average height will be greater in one leaf-colour group than in the other.” For a more specific prediction, the student would need a reason to expect which group would be taller. Keeping growing conditions similar makes the group comparison clearer, but does not show that the groups differ only in the trait being recorded.

Answer: Question: Is average height after three weeks different between the two leaf-colour groups grown under the same conditions? Hypothesis: The groups will differ in average height. Prediction: One group will have a greater recorded average height than the other.

Check: The proposed comparison is measurable. Its result could support or fail to support the hypothesis, but it would not by itself establish a genetic cause.

Common mistakes and how to avoid them

Writing a question that already assumes its answer, such as “Why does extra light make seedlings taller?”

Correction: Use neutral wording, such as “How does daily light exposure relate to seedling height?” The evidence should determine whether a relationship is observed.

Treating a prediction as the hypothesis.

Correction: Keep the roles distinct. The hypothesis proposes an answer or explanation; the prediction states the expected observation if that proposal is supported.

Using vague words such as “better,” “healthy,” or “more active” without defining them.

Correction: Choose an observable measure, such as height in centimetres, number of pill bugs in an area, or heartbeats counted in one minute.

Claiming that a result proves a hypothesis for all organisms.

Correction: Describe what the evidence supports under the conditions studied. A limited investigation cannot automatically establish a universal conclusion.

Lesson summary

A research question focuses an investigation on a biological system, a factor, and an outcome.
A testable hypothesis proposes an answer that can be checked with evidence.
A prediction states the specific result expected if the hypothesis is supported.
Operational definitions make factors and outcomes clear enough to measure.
Interpret conclusions within the limits of the organisms and conditions studied.

Check your understanding

Question 1

Which statement is a prediction for the question “How does water amount affect bean seedling height after two weeks?”

Water is important for plant life.
Seedlings given 20 mL of water each day will have a greater average height after two weeks than seedlings given 10 mL each day.
Why do seedlings need water?
The two groups should be treated fairly.

Show answer and explanation

Seedlings given 20 mL of water each day will have a greater average height after two weeks than seedlings given 10 mL each day.

This statement gives a specific comparison and measurable outcome. The other choices are a broad claim, a question, or a general planning reminder.

Question 2

A student writes, “If snails prefer moist places, then more snails will be counted in the damp area.” What is the most accurate description of this statement?

It is a research question because it asks what is happening.
It is a prediction because it states an expected observation.
It is a measurement because it gives a count.
It is a conclusion because it reports collected evidence.

Show answer and explanation

It is a prediction because it states an expected observation.

The statement gives an expected result. It does not report evidence already collected, and it does not ask a question.

Question 3

Which revision makes “Does light affect plant growth?” more testable?

Does good light make plants much better?
How does the number of light hours each day relate to bean seedling height in centimetres after fourteen days?
Why do all plants need light?
Is sunlight the most important thing for every plant?

Show answer and explanation

How does the number of light hours each day relate to bean seedling height in centimetres after fourteen days?

The revision identifies a factor, a plant system, a measurable outcome, and a time point. The other choices contain vague terms or make claims that are too broad.

Key terms

Research question: A focused question that identifies what an investigation will examine.
Hypothesis: A proposed, testable answer or explanation for a research question.
Prediction: A statement of the specific result expected if a hypothesis is supported.
Independent variable: The factor deliberately changed or compared in an investigation.
Dependent variable: The outcome measured or observed in an investigation.
Operational definition: A precise description of how a factor is set or how an outcome is measured.

Continue through SBI4U

View the complete SBI4U Ontario Grade 12 Biology curriculum and lessons

About this lesson and its review

Published by DoAssignment. This reviewed lesson follows Ontario Grade 12 Biology (SBI4U), expectation A1.1. It is a study resource, not an official curriculum publication.

Before publication, content is checked for structure, mathematical or chemical notation, calculations, course boundaries, and readability. Errors can still occur, so corrections are welcomed.

Official curriculum reference

Report a correction or ask a question