Did the Labour government agree to pay a £92 billion Brexit bill? Did you hear about the second terrorist attack at the Royal Oldham Hospital just minutes after the bombing of Manchester Arena in May? What should we do about the rising crime rate in most major US cities? What about the story that was released prior to the last US election - the one that linked Hillary Clinton to sex crimes with children?

We hope you have caught on: all of these stories have gone viral on the internet - and all are fake.

The truth of these tales is much less exciting. Labour said it would pay what was legally required of Brexit (there was no way at the time of knowing what the cost might be); no secondary attack was carried out at the Royal Oldham Hospital; crime rates in most US cities - and around the world - are generally less than half of what they were in 1990; and Hillary Clinton never headed a paedophile organisation.

Fake news stories such as these are being circulated with increasing frequency, but the problem is not a new one. Efforts have always been made to provide people with deliberately wrong information, which is known as disinformation. But with so many people now using multiple social media sites, it is now easier to spread even ludicrous lies.

So how can we teach our students - and ourselves - what and whom to believe?

The hard work of thinking

After the 2016 US presidential election, social media mogul Mark Zuckerberg was criticised for not stopping the spread of fake news on Facebook. Critics argued that these fake news stories affected the election result. In an open letter posted on Facebook, Zuckerberg acknowledged that steps were being taken to help users identify fake news and hoaxes. The trouble, he argued, was that sorting fact and opinion from fake news is very difficult.

Indeed it is. But critical thinking can help. Or rather, it could if people knew what it really meant and how it could be taught.

Look through the website of your own school and those of others, selected at random - odds are good that they will all claim to develop critical-thinking skills in their students. Similarly, employers consistently list critical thinking as the top skill they want in their employees. But does anyone really understand what it is?

The definitions are many, but they don’t differ all that much. Good or clear thinking reflects a deep understanding and is relatively free of common biases; critical thinkers consider the evidence that supports - and fails to support - a conclusion. They consider the relative strength of different types of evidence, the credibility of the information sources, relevant probabilities, the way language influences how we think, etc.

Here is a definition that one of us (Halpern) has used for decades: “Critical thinking is the use of those cognitive skills and abilities that increase the probability of a desirable outcome. It is used to describe thinking that is purposeful, reasoned and goal-directed - the kind of thinking involved in solving problems, formulating inferences, calculating likelihoods and making decisions, when the thinker is using skills that are thoughtful and effective for the particular context and type of thinking task.”

Critical thinking is also a disposition. Students need to be willing to engage in the hard work of thinking - checking to see if a conclusion is supported by evidence or if an event is likely or unlikely to occur. Learning critical-thinking skills would be futile if students didn’t then put those skills to use when the time called for it.

It is even more difficult when they encounter information that they don’t like. It is easier to agree with information that confirms what we believe to be true, but being open to information that opposes our beliefs is not easy.

So can we teach students to be better thinkers and to develop the disposition to use it? Many think we cannot, but we believe research proves we can.

A large research literature base, cited in Thought and Knowledge: an introduction to critical thinking (5th ed), shows that with applicable instruction, students can improve their critical thinking.

For example, British academic David Moseley and several colleagues worked in 2005 with teams of educators from all sectors of education in England to determine if students actually benefited from explicit instruction in critical thinking. In a carefully worded document, they concluded: “For practitioners, thinking-skills programmes and approaches are likely to improve pupils’ learning. Their use in schools should therefore be supported.”

Similar arguments have been made in the US. In one project, conducted by the first author of this article (Halpern) and Lisa Marin (Marin and Halpern, 2011), researchers went into low-performing schools in California to test different ways of teaching critical thinking. They conducted several studies: some involved parents working with their child, and others involved classes that were assigned randomly to either receive critical-thinking instruction or receive standard instruction. We found that when critical-thinking skills were deliberately taught (the authors labelled each skill, practised it with different examples, and so on), students showed substantial gains in critical thinking, which were not found with standard instruction. The study also found that critical thinking can be taught at any grade level, as long as it is taught in a way that is developmentally appropriate.

Buzzword fatigue

Yet, despite the evidence, not everyone supports the teaching of critical thinking. In our years spent studying it, we have heard it all. For example, a common criticism is that critical thinking is just the new buzzword in education and that it will eventually go away if we ignore it long enough.

In fact, critical thinking has been around for centuries, but we have only started formally studying its effect over the past few decades. (Standard instruction in reasoning, such as studying modus tollens, modus ponens and standard syllogisms, often does not transfer to everyday thinking.)

We have also heard some say that it is not possible to improve thinking skills in our students via instruction. For evidence, critics cite failed interventions.

But, of course, not every intervention will be successful. We need to be clear about what we teach, and we need to teach in ways that make it long-lasting and useful in multiple contexts. We teach writing, speaking and maths skills with the belief that they will transfer to real-world tasks. We do so with the expectation that when students write about different topics, the writing will be improved and they will communicate their ideas effectively to a reader. We teach students how to speak, so that they can make sound, relevant arguments. We teach students maths skills, so that when they need to compute something, they will be able to do it.

Teaching students how to think is no different. Some students learn these skills better than others, and some teachers plan learning activities that are more effective than other teachers. Critical-thinking instruction needs to be based on the science of learning how to think.

Thankfully, there is a large, growing body of evidence to say that thinking skills can be improved in school, which should quiet most objections.

Of course, some are opposed to critical-thinking instruction because they really do not want students to think for themselves.

In 2012, the Republican Party of Texas stated: “We oppose the teaching of higher-order thinking skills (values clarification), critical thinking skills and similar programs that are simply a relabelling of outcome-based education (mastery learning), which focus on behaviour modification and have the purpose of challenging the student’s fixed beliefs and undermining parental authority.” (Later, the party stated that it was a mistake to oppose “critical thinking”.)

What underpins such statements is a deep fear that because thinking skills are taught by educators who are seen as being more liberal, they will somehow brainwash students into believing a more liberal agenda.

Recognising biases

But that is to misunderstand the whole point of teaching critical thinking. A critical-thinking education should not tell students what to think, but it should teach them how to recognise fallacious reasoning, weigh evidence, question the credibility of information, and how the perspective of the person delivering the message can influence the message - including their teacher.

So, what activities could you use in class tomorrow to enhance critical thinking?

The two components of critical thinking are understanding at a deep level, and recognising and resisting fallacies and biases. It is important to realise that, as teachers, it is what we ask students to do that is important in fostering deep learning, not what we do.

For example, to understand a complex text, a diagram or a maths problem, ask probing questions about the material. Asking students to diagram a text, or to write out a maths problem in words explaining what is being solved and why a particular equation is used, or give an example of where a diagram would be useful.

By using verbal, spatial and numerical thinking, we can get students to understand and recall at a deeper level. In the 1960s, Allan Paivio proposed a theory of human cognition known as the dual-coding theory. He argued that our brain processes information as, and represents information in, both verbal and non-verbal systems. Allowing students to practise processing and representing information in both of these systems can lead to deep understanding. If we take the previous example, students draw or diagram the solution to a maths problem (non-verbal) and then write out the solution (verbal). Furthermore, information processed in one mode can activate or cue the memory for the information in another mode.

Another technique: when students make a statement about a belief or a conclusion, get in the habit of asking why they believe it. So, if a student states that dogs are as smart as humans, ask what sort of evidence they are using. Push them a bit. So, their dog knows all kinds of things - what about Susie’s dog, which can barely find its food dish? How is the student defining “intelligent”? Do they really mean as smart as the average human? What sort of evidence would cause that student to change their mind? Can the rest of the class think of a counterexample?

Question everything

The idea is to get them to start questioning other conclusions; who is the appropriate authority for these statements?

Suppose a student states that they believe that nature (biology/heredity) is more important than nurture (environment) in making people smart. This is an example of the “either/or” or “black/white” fallacy, and anyone can be trained to recognise it and avoid it. Could it be both? Why, or why not?

Similarly, students can learn that there is a great deal of variability between members of groups of people, as well as between different groups of people.

This makes “us-and-them”-type thinking problematic, since people vary in many ways and are similar in other ways, so it is not true that all people from one country are bad and those from another country are good.

This sort of stereotypical thinking can be difficult to overcome but, with repeated practice, students can learn that there are good and bad people in every country.

As a final example, students can develop an awareness of the way language can influence thought. Earlier, we used the term “disinformation” instead of “lies”. Which word makes it sound worse? What about the use of the term “friendly fire” for accidentally killing members of your own military or innocent civilians? Do these terms change how people think?

During the last US election, the FBI was “looking into” Hillary Clinton’s emails. Does it feel different if we use “looking into” or “investigating?”

But why does critical thinking matter? There is a growing body of literature demonstrating the impact that critical thinking has on our everyday lives. The second author of this article (Butler) has published several studies (Butler, 2012; Butler, Dwyer, Hogan, Franco, Rivas, Saiz and Almeida, 2012; Pentoney and Bong, 2017) demonstrating that critical thinkers experience fewer negative life events.

In these studies, students and community adults took a critical-thinking assessment and reported whether they had experienced certain life events, which ranged in severity from rather mild (eg, having to pay a late fee for a movie rental, ruining a load of laundry) to severe (eg, excessive credit card debt, sexually transmitted infection), and covered many domains of life (eg, interpersonal, financial, legal, medical, educational). Critical thinkers experienced fewer negative life events, a result that was found in several countries. This research underscores the importance of critical-thinking education.

Teaching critical thinking is both challenging and rewarding. It requires creativity and effort on the part of educators, but what is the risk of not teaching our students to think critically?

Critical thinking has been called the antidote to the chaos of our time. A time when we are bombarded with enormous amounts of information and must determine what is true. A time when facts are considered relative. A time when computers tailor the media you consume based on prior viewing choices, so that you only hear one perspective that likely confirms what you already believe. Let’s teach our students the importance of considering multiple perspectives, so that they can avoid the pitfalls of confirmation bias (seeking out or accepting information that confirms what you already believe and ignoring that which might disconfirm your belief).

Scott Lilienfeld (2007) argued that if we could overcome confirmation bias, we could significantly reduce inter- and intra-group conflict (ie, we achieve world peace). Future generations need to be able to have an open dialogue about controversial issues without resorting to name-calling, as well as considering multiple perspectives, before making important decisions. Our future depends on it.

Diane F Halpern is the dean of social sciences, emerita at the Minerva Schools at KGI, professor of psychology, emerita at Claremont McKenna College, and a past president of the American Psychological Association and the Society for Teaching of Psychology. Her books include Thought and Knowledge: an introduction to critical thinking (5th ed, 2014); Psychological Science (5th ed, with Michael Gazzaniga and Todd Heatherton)

Heather Butler is an assistant professor in the psychology department at California State University Dominguez Hills. Her latest research argues that critical thinking might even be more important to our everyday lives than intelligence. For more information, please visit her webpage at drheatherbutler.com