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A1.9 · Evaluate research sources for reliability and bias

Learn to evaluate research sources for reliability and bias through clear examples and targeted practice.

Ontario Grade 10 Science

Scientific Investigation and Careers

How to judge whether a source is reliable and whether bias may shape its message

Imagine two websites make opposite claims about the same science topic. One has a bright design and confident wording. The other is plain but links to its evidence. Which should you trust? A design or confident tone is not enough to decide. In this lesson, you will use a careful, repeatable process to evaluate sources. A source is material that provides information, such as a webpage, article, report, or interview. Evaluating means making a reasoned judgment using clues you can point to, rather than choosing the source you already agree with.

What you will learn

Explain what reliability and bias mean when evaluating a research source.
Check who created a source, what evidence it gives, and whether its claims match that evidence.
Compare sources without assuming that a polished page or a strong opinion is automatically trustworthy.
Describe limits and possible bias fairly, using specific evidence from the source.

1. Start with what you already know

In earlier science learning, you may have collected observations and used evidence to support a conclusion. Evidence is information that helps support or challenge a claim. A claim is a statement that can be checked. A source may report evidence, explain it, or make a claim based on it.

Reliability means how dependable a source is for the question you are asking. A reliable source gives information that is supported, clear, and possible to check. Reliability is not the same as being perfectly free of mistakes. It is a judgment based on the source’s strengths and limits.

Bias is a tendency to present information in a way that favours a particular view or interest. Bias can affect what a source includes, leaves out, or emphasizes. A source can have a point of view and still provide useful evidence. The key is to notice the point of view and check the evidence instead of accepting every claim.

Before searching, make the question clear. A source can be useful for one question and weak for another. For example, a local report may help explain a local issue, but it may not answer a question about many regions.

Reliability is a judgment about how dependable a source is for a particular question.
Bias may shape what a source says or leaves out; it does not automatically make every detail false.
A claim needs evidence that is relevant to the question.

2. Notice what a source shows and what it leaves unclear

When you open a source, look beyond its headline. Check who created it and when it was published or updated. The creator may be a named author, an organization, or an agency. Ask whether the creator has relevant knowledge and whether you can identify the organization behind the page. A name or title is a clue, not proof that every statement is correct.

Next, find the evidence. Does the source explain where its information came from? Does it show observations, examples, or data that relate to its claim? Data are recorded information, such as counts or measurements. Check whether the source explains what the data describe. A number without context may not tell you much.

Look for a clear link between evidence and claim. If a source reports that a change happened, ask whether the evidence shown actually supports that statement. Notice whether the source discusses limits or other possible explanations. A source that presents only a strong conclusion while hiding important limits deserves closer checking.

Check the date in relation to the question. Some information can change, while other background information may remain useful. A recent date alone does not make a source reliable. Also check whether links or references lead to information you can inspect. A reference is a pointer to where information came from.

Consider purpose. A source may aim to inform, sell, persuade, entertain, or a mix of these. Look for signs such as product links, requests for donations, or language urging readers to take a side. These clues may point to an interest, but do not settle the question by themselves. Ask how that purpose could affect the selection or presentation of information.

Check creator, date, evidence, links, and purpose.
Ask whether the evidence supports the particular claim being made.
Treat clues as reasons to investigate, not as automatic pass-or-fail rules.

3. Compare sources and make a fair judgment

A second source can help you check a claim, especially when it comes from a different creator. Agreement is more useful when sources explain their evidence independently. Two pages that repeat the same original statement do not necessarily provide two separate checks.

Use the comparison table as a reminder. It is not a scorecard where one clue decides everything. Write down specific observations, then explain how they affect the source’s usefulness for your question.

When sources disagree, do not settle the disagreement by counting headlines or choosing the one with the most certain language. Compare what each source actually supports. One may answer a different question, use a different time period, or leave out information. State what is known from the sources and what remains uncertain.

A careful evaluation is balanced. You might say that a source is useful because it names its author and links to supporting evidence, but limited because it does not explain how the information was collected. This is stronger than simply calling it good, bad, or biased.

Compare the evidence and question each source addresses, not just their conclusions.
Repeated claims are not automatically independent confirmation.
Give a reasoned judgment and name both useful features and limits.

4. Use the process safely and honestly

A source evaluation is research work, so keep track of where each claim came from. Do not copy a statement and present it as your own. When you use information, identify the source in the way your teacher requests. Represent what the source says fairly, even if you disagree with it.

Stay on safe, appropriate pages. Do not share personal information, download unknown files, or follow instructions for risky activities just because a page presents them as science. If a source suggests an unsafe experiment, do not try it. Ask your teacher to help assess the information.

Your conclusion should fit the evidence you checked. Use careful wording such as “This source appears useful for this question because…” or “I cannot confirm this claim from the evidence shown.” That wording makes your reasoning clear without pretending to know more than the sources establish.

Keep track of sources and describe their claims accurately.
Do not follow unsafe instructions found online.
Match the strength of your conclusion to the evidence you actually checked.

A source-checking guide

Check	Ask yourself	Possible clue
Creator	Who made this, and can I identify them?	Named author or clear organization
Evidence	What information supports the claim?	Described observations, examples, or data
Fit	Does that evidence answer my question?	Claim matches the group, place, or time described
Date and links	Can I check where the information came from, and is the date suitable?	Working references and a relevant date
Purpose and limits	Could an interest shape what is emphasized? What is missing?	Sales link, one-sided wording, or an unstated limitation

Worked example

A confident claim with little support

Hypothetical example: A webpage says, “Our study proves that every student learns better with a certain study app.” It does not name an author or describe the study. The page has a link to buy the app. Evaluate the source for the claim.

Identify the claim
The claim is that the app improves learning for every student. The word “every” makes a very broad statement, so the source would need evidence that fits that broad claim.
Inspect the support and purpose
The page gives no author and does not describe the study. The purchase link suggests a sales interest. That interest could affect what the page emphasizes, but it does not by itself prove the claim false.
Reach a limited judgment
The webpage is weak support for this claim because readers cannot check the study or judge how well its evidence fits the statement. A fair judgment is that the claim is not established by the information shown.

Answer: The source has warning signs: missing authorship, no described evidence, and a sales link. It is not enough to establish that the app helps every student.

Check: The judgment points to specific clues and does not claim that a sales interest automatically makes the statement false.

Worked example

A source with useful evidence and a clear limit

Hypothetical example: A school report names its authors, gives the date, and describes a voluntary student survey about a new lunchtime program. It reports that 36 of 60 respondents liked the program. The report does not say how students who did not answer might differ. Is it reliable for judging whether all students like the program?

Check the claim against the evidence
The report supports a limited statement: 36 of the 60 respondents said they liked the program. It does not directly show what all students think.
Consider how the information was gathered
The survey was voluntary. Students who chose to answer may differ from those who did not. This is a possible source of bias in the responses, because the group answering may not represent all students.
State the strength and limit
The named authors, date, and described survey make the report easier to check. The missing information about non-respondents limits how well it can answer the question about all students.

Answer: The report is useful for describing the 60 responses, but it is limited evidence for what all students think. Do not change “respondents” into “all students.”

Check: The conclusion stays within the group actually described and identifies a reasonable limitation.

Worked example

Two sources that appear to agree

Hypothetical example: Two webpages state that a city park has more litter on weekends. The first page describes observations on four weekends and gives dates. The second page repeats the first page’s statement and links back to it, but provides no observations of its own. What can you conclude?

Trace where the claims came from
The second webpage points back to the first. It repeats the claim rather than reporting a separate set of observations.
Match the evidence to the claim
The first page gives dates and observations from four weekends. That can support a statement about those observations. It does not automatically describe every weekend or prove why litter was present.
Avoid overstating agreement
There is one described set of observations, not two independent checks. The evidence may be useful for the specific weekends, but more information would be needed for a broader conclusion.

Answer: The webpages do not provide two independent confirmations. The first supports a limited observation about four weekends; the second repeats it.

Check: Tracing the link reveals that the apparent agreement comes from the same original information.

Common mistakes and how to avoid them

Trusting a source because it looks professional or uses confident language.

Correction: Check who created it and what evidence supports its claims. Appearance and confidence do not show that evidence is dependable.

Calling a source false as soon as you notice a possible bias.

Correction: Explain how the possible interest could affect the information, then examine the evidence. Bias is a reason to check carefully, not automatic proof of falsehood.

Treating two pages that repeat one claim as two separate confirmations.

Correction: Follow links and references to see whether each source provides its own evidence.

Using a small or limited set of responses to make a claim about everyone.

Correction: Name the group and conditions the evidence actually describes, and state what it cannot establish.

Lesson summary

Evaluate a source for a particular question, not in the abstract.
Check its creator, evidence, fit to the claim, date, references, purpose, and limits.
Bias may shape a source, but it does not automatically make every statement false.
Compare the underlying evidence and trace repeated claims to their original source.
Make a fair judgment that is no broader than the evidence allows.

Check your understanding

Question 1

A page makes a science claim but gives no evidence and asks readers to buy a product. What is the best first judgment?

The claim must be false because the page sells something.
The page needs closer checking because it gives no evidence and may have a sales interest.
The claim is reliable because the page sounds certain.
correctIndex: 1,

Show answer and explanation

The page needs closer checking because it gives no evidence and may have a sales interest.

A sales interest and missing evidence are reasons to check the source carefully. They do not prove the claim false, and confident wording does not prove it true.

Question 2

A voluntary survey reports the views of students who chose to respond. Which statement is best supported?

All students share the views reported.
The responses describe the students who answered, while other students may have different views.
The survey has no value because it was voluntary.
correctIndex: 1,

Show answer and explanation

The responses describe the students who answered, while other students may have different views.

The reported responses describe respondents. Because answering was voluntary, the results may not represent students who did not answer.

Question 3

Two webpages repeat the same claim, and the second links to the first without adding evidence. How many separate sets of evidence are described?

Two, because there are two webpages.
One, because the second page repeats the first source.
None, because webpages cannot provide evidence.
correctIndex: 1,

Show answer and explanation

One, because the second page repeats the first source.

The second page does not add its own observations or other evidence, so the pages describe one underlying set of information.

Key terms

Claim: A statement that can be checked.
Evidence: Information that helps support or challenge a claim.
Reliability: How dependable a source is for a particular question.
Bias: A tendency to favour a particular view or interest when presenting information.
Data: Recorded information, such as counts or measurements.
Reference: A pointer to where information came from.

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About this lesson and its review

Published by DoAssignment. This reviewed lesson follows Ontario Grade 10 Science (SNC2D), expectation A1.9. 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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