Today I continue to put down the student misconceptions on forces and motion as reported from physics education research.
Every physics teacher will encounter the misconceptions every time when they teach force and motion. It is inevitable because of the “mismatch” of what was taught with the daily life experience. However, there is actually no mismatch because the daily life experience is more complicated than what was taught in physics class. Students are learning how to properly analyze motions from teachers. Daily life situations are complicated, so we tend to simplify and generalize them. That will lead to incorrect conclusions when students try to link them with what was taught in physics.
Research papers discussed:
- Common sense concepts about motion by Halloun and Hestenes.
- Force Concept Inventory by Hestenes, Wells, and Swackhamer.
- Systematic study of student understanding of the relationships between the directions of force, velocity, and acceleration in one dimension by Rosenblatt and Heckler
Research findings by Halloun and Hestenes
Here are some findings reported by Halloun and Hestenes. (We mentioned this paper in the previous post.)
- Every motion is started by a force, sustained by a force, and may be opposed by resistive forces.
- Greater mass exerts greater force during collisions.
- When there are more than one force acting on the object, students may only consider the effects due to the stronger force or a vague form of compromise.
- Constant velocity means constant force, acceleration means increasing force.
- Constant force has limited effect – it can wear out due to other resistive force or has no effect after certain velocity.
- An internal force (impetus) is required for object to continue moving.
- Some students wrote
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Research findings by Hestenes, Wells, and Swackhamer
This Force Concept Inventory (FCI) paper is a continuation of the Halloun and Hestenes paper. This 30-item survey was administered to high school and college students in the form of pre-post instruction to assess learning gains. It has been used by many researchers and instructors and numerous papers are published. It is the mostly cited PER journal as it also started a new research area on instruments to assess student learning.
It showed the usual one-way transfer instruction was not effective in addressing student misconceptions. Many journals have reported that active-learning strategies are effective in improving student understanding.
Research findings by Rosenblatt and Heckler
As student understanding on force and motion has been deeply researched, they chose to study how students relate the directions of velocity and acceleration, velocity and force, and acceleration and force. Here are what their findings suggest:
- Introductory students tend to relate the direction of velocity to the direction of force and vice versa.
- Students tend to relate zero net force to zero velocity and vice versa.
- Students tend to relate the direction of acceleration to the direction of velocity and vice versa.
My take on this misconception
After interacting with numerous students for the past 10 years, these misconceptions are just common. It’s part of the students’ learning journey. I believe, anecdotally, these reasons contributed to the misconceptions:
- Students are not fluent in applying the definitions of velocity, acceleration, and net force.
- Students use “acceleration” and “force” in daily life to describe the motion in an unprecise manner.
My point being, as much as all these physics terms are defined in words and expressed in mathematical formula, they are new to students after all. Just like we teach our kids to use knife to julienne potatoes or carrots, why one should expect a beginner to do perfect julienne after 1-2 lessons and discussions. It takes time for them to get better. More opportunities and reinforcement of correct concepts are needed to improve student understanding.
That’s all from me. Feel free to comment below!
Chang Physics Class 