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A1.1 · Form scientific questions, predictions, and hypotheses

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

Ontario Grade 10 Science

Scientific Investigation and Careers

Turning an observation into a clear, testable idea

A plant near a classroom window looks taller than a similar plant farther from the window. That is an observation: a description based on what someone notices. It may lead to a scientific question, such as whether the amount of light affects plant growth. A prediction says what result you expect. A hypothesis gives a possible explanation and a result that could be checked. These ideas help turn curiosity into an investigation. In this lesson, you will practise forming them without treating an expectation as a proven fact.

What you will learn

Tell the difference between an observation, a scientific question, a prediction, and a hypothesis.
Form questions that can be investigated using evidence.
Write predictions that state an expected result.
Write hypotheses that connect a possible explanation to an expected result.

From an observation to an investigable question

In Grade 9 science, you learned to notice patterns and use evidence. An observation is information gathered by seeing, hearing, measuring, or otherwise noticing something. It should describe what was noticed, rather than explain why it happened. For example, “The soil in this pot feels drier than the soil in the other pot” is an observation. “The plant used all the water” is an explanation, and it has not yet been checked.

A scientific question asks about something that can be investigated with observations or measurements. It should be focused enough that someone can decide what evidence would help answer it. The question “Why do plants grow?” is too broad for a simple investigation. A more focused question is, “Does the number of hours of light each day affect the height of these plants over two weeks?”

A useful question identifies what is being changed or compared and what will be observed. The factor being changed or compared is called the independent variable. The outcome being observed or measured is called the dependent variable. These terms name parts of a question; they do not guarantee that an investigation will give a clear answer. Here, daily light exposure is the independent variable, and plant height is the dependent variable.

A question is not a good scientific question just because it includes the word “why.” Questions about opinions or matters that cannot be checked with evidence may not be suitable for a scientific investigation. Before choosing a question, ask: What could I observe or measure? What evidence might help answer it? Is the question narrow enough to investigate safely and fairly?

An observation describes what was noticed.
A scientific question can be investigated using evidence.
A focused question names a factor to compare and an outcome to observe.

Predictions and hypotheses

A prediction states what you expect to observe if a question is investigated. It is about an expected result, not a guarantee. For example: “If the plants receive more hours of light each day, then I expect their average height after two weeks to be greater.” This prediction names a comparison and an outcome. The result might not match the expectation.

A hypothesis is a possible explanation that can be checked with evidence. It links an explanation to an expected result. For example: “If plants receive more hours of light, they may grow taller because light helps them make the food they need; therefore, plants given more daily light are expected to be taller after two weeks.” The explanation is a proposal, not a fact established by this statement.

Predictions and hypotheses are related, but they are not identical. A prediction focuses on what result is expected. A hypothesis includes a proposed reason for that expectation. In school investigations, the wording can vary, so make the difference clear: state the expected result, and, when asked for a hypothesis, also state the possible explanation.

A useful prediction or hypothesis can be checked. Avoid wording such as “The plants will do better,” because “better” is not clear evidence. Say what you will observe, such as plant height, and when you expect to observe it. A hypothesis should also be written so that evidence could fail to support it. If every possible result is said to prove the explanation, the idea cannot be fairly checked.

A prediction states an expected result.
A hypothesis proposes an explanation and connects it to an expected result.
Neither one is proof; evidence may support or not support the idea.

Use evidence carefully and safely

A scientific idea becomes more useful when it is connected to observable evidence. Before an investigation, identify what result would count as evidence for or against the prediction. Use clear descriptions and, when appropriate, measurements. Do not change an observation to make it fit an expectation.

A fair comparison needs attention to other factors that could affect the result. For the plant example, different starting sizes, watering, or soil could also affect height. Thinking about these factors helps you form a clearer question and prediction. It does not mean you must assume that one factor is the only cause.

Evidence should be gathered in a safe, suitable way. Follow classroom directions and use teacher-approved materials and procedures. Do not try an experiment at home if it could involve unsafe materials or conditions. A question can be scientifically interesting even when a particular way of investigating it is not safe or practical.

When evidence does not match a prediction, that is still useful information. It may mean the prediction was not supported under the conditions observed, or that the question, explanation, or investigation needs reconsideration. Do not claim that one result proves a broad explanation. State what was observed and keep the conclusion within the evidence.

Decide what observable evidence relates to the question.
Consider other factors that could affect an outcome.
Use safe, approved procedures and report observations honestly.

A simple model for planning your thinking

Use this sequence to keep the parts of an inquiry distinct: observation, question, prediction, and hypothesis. Each part has a different job. The observation gives a starting point. The question identifies what you want to find out. The prediction states an expected result. The hypothesis adds a possible explanation for that result.

For example, suppose two identical paper towels seem to absorb different amounts of water. The observation is that one towel appears wetter after use. A focused question could ask whether towel brand affects the amount of water absorbed under the same conditions. A prediction would state which brand is expected to absorb more. A hypothesis would add a possible reason, such as a difference in the towels’ material or structure. That reason still needs evidence.

The model is a thinking aid, not a rule that every investigation must follow in exactly the same order. You may revise a question when you realize that it is too broad or cannot be checked safely. Keep the wording precise enough that another person can understand what evidence would address it.

Keep observations, questions, predictions, and hypotheses separate.
A possible explanation in a hypothesis still needs to be checked.
Revise unclear questions before deciding what result to expect.

Four parts of scientific thinking

Part	Purpose	Example
Observation	Describe what was noticed	Snow remains longer in a shaded patch.
Question	Ask what can be investigated	Does sunlight affect how long snow remains?
Prediction	State an expected result	Snow in the sunny patch is expected to disappear sooner.
Hypothesis	Give a possible explanation and expected result	Sunlight may warm the snow, so it is expected to disappear sooner in the sunny patch.

Worked example

Turn a classroom observation into a question

A student notices that a shaded patch of snow remains longer than a nearby sunny patch. Form an observation and a focused scientific question. Do not claim a result that has not been measured.

State only what was noticed
The observation is that snow appears to remain longer in the shaded patch. This describes a noticed difference. It does not yet say what caused the difference.
Choose an outcome to compare
The question can compare how long snow remains in sunny and shaded locations. The time until the snow is gone is an observable outcome.
Write a focused question
A suitable question is: “Does the amount of sunlight affect how long snow remains in a patch?” It can be investigated by observing the snow in the two locations. The question does not assume that sunlight is the only factor involved.

Answer: Observation: Snow appears to remain longer in the shaded patch than in the nearby sunny patch. Question: Does the amount of sunlight affect how long snow remains in a patch?

Check: The observation reports what was noticed, and the question identifies a comparison and an observable outcome.

Worked example

Separate a prediction from a hypothesis

A class asks whether the colour of a container affects how quickly ice melts in it. Write a prediction and a hypothesis. Treat the ideas as expectations, not measured results.

Name the result to observe
The class needs a clear outcome. It could observe the time taken for the ice in each container to melt. No result should be reported before the observation is made.
State an expected result
One possible prediction is: “If identical ice pieces are placed in containers that differ only in colour, I expect the ice in the darker container to melt sooner.” This states an expected comparison that evidence could support or fail to support.
Add a possible explanation
A possible hypothesis is: “The ice in the darker container may melt sooner because the darker surface may take in more light energy.” This is a proposed explanation, not a confirmed fact about the class’s containers. The class would need evidence to assess it.

Answer: Prediction: The ice in the darker container is expected to melt sooner. Hypothesis: It may melt sooner because the darker surface may take in more light energy.

Check: The prediction names an expected result. The hypothesis adds a possible reason that can be checked.

Worked example

Improve a vague question

A student asks, “Do people learn better with music?” Improve the question so it names a comparison and an observable outcome. Then give a cautious prediction.

Make “better” observable
The word “better” is unclear. A specific outcome, such as the number of correct answers on the same short review task, gives a way to compare results.
Narrow the comparison
A clearer question is: “For students completing the same short review task, does working with quiet instrumental music instead of silence affect the number of correct answers?” This question identifies two conditions and an outcome.
Make a cautious prediction
One possible prediction is: “I expect students in silence to answer more questions correctly.” This is only an expectation. The question does not establish that either condition is better, and any investigation would need to be safe, appropriate, and approved by the teacher.

Answer: Question: For students completing the same short review task, does working with quiet instrumental music instead of silence affect the number of correct answers? Prediction: I expect students in silence to answer more questions correctly.

Check: The revised question replaces a vague outcome with something observable and states the comparison clearly.

Common mistakes and how to avoid them

Writing an explanation as if it were an observation.

Correction: First report what was noticed. Label a possible cause as an explanation or hypothesis until evidence has been gathered.

Using a vague question such as “Does it work better?”

Correction: Name what is being compared and choose an outcome that can be observed or measured.

Treating a prediction as a guaranteed result.

Correction: Use wording such as “I expect” and remember that evidence may not match the prediction.

Calling a prediction a hypothesis without giving a possible reason.

Correction: A prediction states the expected result. A hypothesis also proposes an explanation that can be checked.

Saying that one result proves a broad explanation.

Correction: Describe what the evidence supports in the situation studied. Do not claim more than the evidence can show.

Lesson summary

An observation describes what was noticed.
A scientific question asks about something that evidence can help answer.
A prediction states an expected result.
A hypothesis proposes an explanation and connects it to an expected result.
Make ideas clear, checkable, and safe to investigate.

Check your understanding

Question 1

Which statement is an observation rather than an explanation?

The water in this cup looks cloudier than the water in the other cup.
The cup is cloudy because it contains more minerals.
The minerals made the water change.
Cloudy water is always unsafe.

Show answer and explanation

The water in this cup looks cloudier than the water in the other cup.

This statement describes what was noticed. The other choices propose causes or make a broad claim.

Question 2

Which is the most focused scientific question?

Why do living things need things?
Are plants good?
Does the amount of water given to these seedlings affect their height after one week?
Will every plant grow well?

Show answer and explanation

Does the amount of water given to these seedlings affect their height after one week?

It identifies a factor to compare, an outcome to observe, and a time frame.

Question 3

A student writes, “If the paper towel is wider, I expect it to absorb more water.” What has the student mainly written?

An observation
A prediction
A measured result
A confirmed explanation

Show answer and explanation

A prediction

The statement gives an expected result. It does not report an observation or provide a possible explanation.

Key terms

Observation: Information noticed using the senses or a measuring tool.
Scientific question: A focused question that can be investigated using evidence.
Prediction: A statement of the result someone expects to observe.
Hypothesis: A possible explanation that connects to an expected result and can be checked with evidence.
Independent variable: The factor that is changed or compared in a question or investigation.
Dependent variable: The outcome that is observed or measured.
Evidence: Observations or measurements used to help answer a scientific question.

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About this lesson and its review

Published by DoAssignment. This reviewed lesson follows Ontario Grade 10 Science (SNC2D), 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.

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