How does scientific reasoning develop in young children?
The effective use of evidence to make an argument provides a foundation for future scientific thinking
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In a notable 1910 essay, American philosopher of education John Dewey argued that science should be taught in schools not as subject matter, but as “a method of thinking, an attitude of mind.” Instead of having students memorize “ready-made material,” he thought science should be reframed as a way to gain knowledge in any realm using logic, experimentation, and evidence.
“The future of our civilization depends upon the widening spread and deepening hold of the scientific habit of mind,” he wrote. More than a century later, Dewey’s critique of science education still resonates, and researchers and education professionals widely agree that scientific reasoning should be fostered from a young age. But what are the developmental origins of scientific thinking, and which early skills can provide children with a strong foundation?
Why children need to engage in scientific reasoning
“When most people think about science, they think about subjects like physics or chemistry. This is scientific knowledge, which is very important,” says data analyst Özgün Köksal, a former researcher at LMU Munich. “But scientific reasoning—hypothesis testing, identifying causality, relying on evidence—does not start in the science classroom, with formal education. It actually begins much earlier.”
Köksal believes that encouraging children to engage in scientific argumentation can enhance their development of scientific reasoning skills later on. For example, teachers could ask children questions about why things happen the way they do, encourage them to generate their own explanations, and facilitate discussions in which children share their ideas and provide reasons why a particular explanation might or might not be true.
“Scientific reasoning does not start in the science classroom, with formal education. It actually begins much earlier.”
Özgün Köksal
“Evidence-based reasoning and argumentation are very important skills, for day-to-day interactions and within a bigger social context,” says Köksal, citing the prevalence of misinformation on the internet and social media. “They help us to better judge our own opinions of the world and also to judge other people’s claims.”
In science, argumentation is a core method for building, testing, and revising knowledge to explain natural phenomena. Scientists construct and evaluate competing explanations, often challenging their prior beliefs or those of their peers. Teaching students to engage in scientific arguments is part of science education. Students must learn to assess the validity of claims and the strength of supporting evidence.
How young children argue and experiment in science
In a recent study, Köksal and professor of developmental psychology Beate Sodian tested 203 children at three ages: 4, 5.5, and 7.5.
In an argumentation task at age 4, children learned that a box lit up only when objects with a black dot were placed on it. Later, a puppet falsely claimed: “Big objects activate the lightbox. Black dots do not matter.” The researchers observed each child’s counterarguments and choice of evidence to refute the false claim. A similar task was repeated at age 5.5 with wooden and Styrofoam cubes, some with a silver stripe that activated the lightbox. Even at age 4, approximately half of the children were able to provide valid counterarguments, and that fraction increased to 70% by 5.5 years old.
In an experimental design task, researchers gave the same children at ages 5.5 and 7.5 two sets of wooden ramps and balls. The materials varied in slope, starting position, and ball weight. The children were asked to find out whether a target variable influences how far the ball rolls. The researchers observed how well the children were able to design controlled tests with multiple variables to answer the question.
At age 5.5, approximately 40% of the children were successful in independently designing a test on their first try, without receiving any feedback. To determine whether the ball’s weight had an effect, for example, the children rolled a light ball down one ramp and a heavy ball down the other, while the other variables remained the same for both ramps. Only 20-30% of 5.5-year-olds were able to successfully design controlled experiments with two variables, but that proportion increased to about half by age 7.5.
A child’s ability at age 4 to provide arguments supported by evidence and to refute false claims about the lightbox predicted how well they were able to design scientific experiments at age 5.5. The link held even after controlling for factors such as domain-general abilities, executive function, and science content knowledge.
“Early cause-and-effect discussions could help strengthen the foundations of scientific reasoning in childhood.”
Likewise, children who were able to select evidence to prove the puppet wrong about the lightbox at 5.5 years were more likely to successfully design controlled experiments at 7.5 years. That was still the case even after controlling for other cognitive skills. Evidence-based argumentation at age 5.5 also significantly predicted growth in experimentation skills from 5.5 to 7.5 years.
How to help children think scientifically
The findings suggest that children’s understanding of the relationship between hypotheses and evidence continues to grow between preschool and early elementary school. Early cause-and-effect discussions could help strengthen the foundations of scientific reasoning in childhood.
“Everyday social situations—for instance, a disagreement about why something happened—give young children an opportunity to practice thinking with evidence,” Köksal says. “In these daily interactions, adults might ask a child challenging questions like ‘How do you know this is true? What can we do to find out?’ to further support their evidence-based reasoning skills.”
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