Student Conception: Frames of Reference

[Matt Anthes-Washburn]

Student Conception: Frames of Reference
Students may not recognize or apply reference frames appropriately.  Students tend to consider true motion as the motion of an object relative to the Earth.   There are examples that students have an easier time combining relative velocities than computing distances based on relative paths of travel.  Distances are considered to be frozen in a geometrical space independent of observers and reference frames. 
(Saltiel, E., Malgrange, J. L., (1980) ‘Spontaneous’ ways of reasoning in elementary kinematics, European Journal of Physics, pp. 73-80.)

Identifiers
Students will describe velocities relative to moving frames of reference as “apparent” velocities or “observed” velocities.  Students say, “It looks like the ball is moving 2 m/s”, instead of correctly stating, “the ball is moving 2 m/s relative to observer A.”

Formative Assessment Question
Select a row in front of some students and behind others, so half the class turns back to see you and the other half looks forward.  Walk from one side of the classroom to the other.  Then ask students if you walked to the right or to the left.  Students will disagree, depending on their perspective. Ask students how you can all see the same thing but some say you went left and some say you went right.

Interventions
The PTG questions contain good examples for calculating relative velocities in different reference frames.  Questions 6-10 all deal with relative velocities.  Question 9 requires students to calculate a reference frame velocity and also to transfer the idea of inertia to a sporting event.  This question would be a good choice to review verbally in the class.
A student in a rolling chair can demonstrate this phenomenon.  It is fine to leave students wondering at this point, as the chair demonstration will be introduced in activity # 4, Projectile Motion.
This activity does not ask students to consider distances from different reference frames.

[Jeff Briggs]

  Looks like good info Mateo - Thanks for the effort!!!

[Tracy Greeley-Adams]

Thank you for explaining the PTG questions so I was able to assign the homework without having to spend too much time looking at what they were asking for.
 

[Donna Wolz]

Looks terrific, Matt!!

[Sushma Sharma]

Hi
this activity works great for my special education  kids.  

[Pete Flores]

Matt, you da Bomb!

[Sandy Shutey]

Good insights

[Dan Wood]

 Matt, Good Info on your misconceptions.

[Kristie Reighard]

Student Conception: Frames of Reference
Students may not recognize or apply reference frames appropriately.  Students tend to consider true motion as the motion of an object relative to the Earth.   There are examples that students have an easier time combining relative velocities than computing distances based on relative paths of travel.  Distances are considered to be frozen in a geometrical space independent of observers and reference frames. 
(Saltiel, E., Malgrange, J. L., (1980) ‘Spontaneous’ ways of reasoning in elementary kinematics, European Journal of Physics, pp. 73-80.)

Identifiers
Students will describe velocities relative to moving frames of reference as “apparent” velocities or “observed” velocities.  Students say, “It looks like the ball is moving 2 m/s”, instead of correctly stating, “the ball is moving 2 m/s relative to observer A.”

Formative Assessment Question
Select a row in front of some students and behind others, so half the class turns back to see you and the other half looks forward.  Walk from one side of the classroom to the other.  Then ask students if you walked to the right or to the left.  Students will disagree, depending on their perspective. Ask students how you can all see the same thing but some say you went left and some say you went right.

Interventions
The PTG questions contain good examples for calculating relative velocities in different reference frames.  Questions 6-10 all deal with relative velocities.  Question 9 requires students to calculate a reference frame velocity and also to transfer the idea of inertia to a sporting event.  This question would be a good choice to review verbally in the class.
A student in a rolling chair can demonstrate this phenomenon.  It is fine to leave students wondering at this point, as the chair demonstration will be introduced in activity # 4, Projectile Motion.
This activity does not ask students to consider distances from different reference frames.

[Kristie Reighard]

Just seeing if this is working from my school computer.

[Sushma Sharma]

Also basic definition of motion helped my student.we defined motion of an object as change in its position with respect to its surroundings (specify). And difference in initial and final positions as a distance covered. Each group had to give example of a moving object using two frames of reference.   
Sushma