Introduction to Evidence-Based Undergraduate STEM Teaching 


Week 1 - Prior Knowledge

There are two types of prior knowledge that students can have when entering a classroom. First, they can have misconceptions about the world around them that need to be addressed and corrected. Second, they can have useful prior knowledge that needs to be activated and built upon so that they can gain deep understanding of more complex ideas.

Misconceptions

Misconceptions in STEM are surprisingly universal. Almost all first year physics students make the same mistakes on standardized quizzes. In many cases, they have the tools to figure out the right answer; they know how the important equations work, but cannot connect those equation with their own conceptual understanding. Thus, their misconceptions inhibit them form acquiring deeper knowledge.

Mental Models

tudents may form "mental models" about the way the world works. These models may be based off of information they learn in a classroom, but more often they are based on instinct or incorrect/incomplete analogies.When students encounter new information in the classroom, they will try to fit that new information into their preexisting mental models. It can be very difficult to convince students to alter these models, since they are often carried with them for years before they are ever addressed and shown to be incorrect/incomplete. As an example, the "Private Universe" video shows Harvard students at their graduation. They have all taken introductory physics courses where they learned about the causes of the seasons on Earth. But most people "learn", at one point in their lives, that the Earth orbits the Sun in a highly elliptical orbit, spending some time quite close to the Sun and some time far away from the Sun. This is an incorrect mental model. When asked about the cause of the seasons, students will revert back to trusting this model rather than relying on the correct information they learned in their classrooms.

Categories of Misconceptions

Not all misconceptions are created equal. Some are easier to correct than others. Here are some types of misconceptions:

1. Proposition-Level Misconceptions

As an example, many people believe that "we only use 10% of our brains." This is a misconception in neuroscience that is heavily supported by pop culture. As soon as a person is told that it is untrue, and that human beings are capable of using more than 10% of our brains, their reaction will likely be "Oh. OK," and they will have corrected their misconception. This is easy to fix, since it's not tied to any other belief systems. 

2. Flawed Mental Models

An example of this is that blood travels through the body in a single loop, originating and terminating at the heart. In reality, the body has two loops, one passing through the lungs where the blood is oxygenated. The single-loop model is never taught to students, yet their basic understanding of the human body leads them to create this mental model. The problem is that this model is somewhat coherent. Students receiving new information can fit it into this model. For example, when asked where the lungs fit in, students might say that they are one of many organs in the single-loop path. To correct the students' misconception, teachers need to challenge their model. If it is indeed flawed, it will breakdown when exposed to logical issues. For example, a teacher could ask the students to explain how oxygen gets into the blood. The single loop model has no explanation for this.

3. Ontolological Miscategorizations

These are misconception based on incorrect or incomplete metaphor use. Students may create metaphors or analogies for complex topics in order to make sense of the material. Sometimes teachers will even provide these metaphors for students. The problem arises when students encounter the limitations of the metaphors and do not realize it. For instance, in astrophysics, we talk about the "fabric of space-time" to explain the action of gravity across large distances. But students have trouble extending that metaphor to make sense of black holes, which would constitute a "rip" in that fabric.