Name: Evaluating Sources & Fact Checking: Crash Course Scientific Thinking #6
Uploaded: 2026-03-10T22:31:25.000Z
Duration: 10 min 14 s
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Are you eating a credit card's worth of plastic every week?

The second conditional

But if you saw headlines like this, you might worry that you are these days, trying to piece together what to believe can feel impossible.

But we can still find reliable, trustworthy answers as long as we know how to look for them.

Hi, I'm Hank Green, and welcome to Crash Course Scientific Thinking.

You probably already know that you shouldn't believe everything you read, watch or hear.

On an Internet where everyone is competing both for attention and to control narratives, it's no surprise that there are plenty of distortions, exaggerations, baseless claims, propaganda, and

But it's also home to lots of good scientific information, too.

So when it comes to something as important as science, how do we figure out what's wrong?

Well, it helps to understand how a science story like this becomes news in the first place.

See, that CNN article isn't the whole story.

It's just the part we see as consumers of science news that science news tastes bad.

There's a lot more going on below the surface.

CNN got the details from this report by the WWF.

No, not the wrestling group from the 90s, the Worldwide Fund for Nature.

And they got it from a study they commissioned from Australia's University of Newcastle, which reported a range of possible amounts of plastic that people might consume in a week, from a high of 5 grams all the way down to 0.1 grams.

But the WWF only reported the high end of the range, saying an average person could be ingesting approximately 5 grams of plastic per week, about the size of a credit card.

There's a lot of things that could be true.

It's like when an insurance company says, I could save you up to 15% or more on your car insurance.

Well, different kinds of publications have different kinds of goals.

And as a savvy consumer of science media, it's helpful for you to consider what those goals might be like.

The WWF is a nonprofit advocacy group whose goal is to preserve nature through lobbying and research.

So they might really want to sound the alarm about microplastics in order to bring people into their broader mission.

Considering an outlet's goals gives us as consumers more information to consider.

It gives us a broader context than just the storywood alone.

And while I would agree that microplastics are a big deal, only Reporting on the upper range to make the situation feel more urgent and headline worthy can make a situation seem a lot more dire than it actually is and intentionally or not, be misleading.

News organizations, by the way, also have goals that we should take into consideration.

Like the goal to get a lot of people to click on an article.

And a headline that says you might eat between a tenth of a gram and five grams of microplastics every week is not going to get the clicks.

What gets reported in the news is sometimes different from the information in the primary source, the firsthand account from the scientists who actually conducted the study.

The primary source is the most accurate representation of what the scientists who conducted the research actually found.

In this particular instance, the primary source was the study from the researchers at Newcastle who reported a range of possible amounts of plastic ingestion.

So what happened between the primary source and cnn?

Well, the Newcastle team got their results and shared them with the wwf.

It was then written into a report by consultants who had not conducted the research directly in what we would call a secondary source.

And this secondary source only listed the upper range of plastic we could be eating.

Those are the numbers that got picked up by cnn.

In science, news articles are often tertiary sources.

They summarize the information of primary and secondary sources, usually not written by scientists.

Sometimes when science gets reported, it can also get distorted.

Someone somewhere along the way got their facts mixed up.

We call that misinformation, information that is wrong or misleading.

But because, as the kids say, we live in a society, we also have to worry about disinformation, information that is intentionally misleading or false.

None of this means that we have to stop trusting reputable news organizations or even advocacy organizations like the WWF wholesale.

It just means we need to be more diligent when we are consuming news.

And good science journalists have learned to navigate the scientific community.

They often have experts they can reach out to for second opinions.

And they present useful context behind a story to help the reader understand how the news fits into larger conversations in science.

How can we, as non scientists and non journalists dig down and figure out when a story is reliable and when it isn't?

It's a way of evaluating sources developed by digital literacy expert Mike Caulfield from the University of Washington.

Stop when you see something that triggers a strong Emotional response, you should stop and really think about what you're reading.

So don't immediately text everyone I know and tell them that they could book a flight with all the microplastics inside of them.

The place that published the information.

How do we find out if CNN is a reputable source?

Well, we know they've been around for over 40 years, but let's investigate a bit further.

So let's open a new tab and get the scoop on cnn.

It looks like they're in the green zone on this media bias chart from Harvard Library's research guides.

Checking other websites, newspapers and media guides like this one to make sure that the source you're getting the original information from is on the up and up.

So if the original source is trustworthy, then we're good.

Up next is f find better coverage using those same lateral reading skills.

We need to check if other sources are reporting the same thing.

In this case, we can find some other sources citing the credit card station, but

we can also find reputable sources saying that it's misleading.

If other reputable sources are disagreeing, it's a sign to take the source you found with a grain of salt.

If other sources are agreeing, then it's a good sign you can dig deeper into what you read.

So you've got to read not just beyond the headline, but

beyond the first source, especially before you share it.

Then you won't be surprised to hear the T. T is for trace claims to their original context.

Often when we see quotes or images online, they're being taken out of context.

So tracing them back to their origin can help us figure out if we're seeing the whole story.

In this case, the CNN article tells us that the credit card claim comes from the WWF article, which CNN links to.

There we can see that they got the claim from this original study.

And here we can see the information in its original context, which stated humans may ingest 0.1 to 5 grams of microplastics weekly.