a collaborator friend teacher tested the worksheet and gave good feedback
below are the comments and my proposed solution to co-developed the lesson.

Based on the pages in the word doc:

Page2, last paragraph, line 2. I was initially confused by the y-direction force indicated. It's after tinkering that i realised your Z is vertical, y is horizontal. Could be a potential confusing point for my students.

[b][color=blue]solution:
implemented decoration = axes[/color][/b]

Page 4: In Qn4, the attached ss of the sliders is very dark, especially the 2nd and 3rd one. Guess the students can refer to the simulation for these.

Page6: Qn11. Sorry, i dotn know the answer to this. Qn 10 seems to be wanting me to know the coil might be pulled apart if the forces are large enough. . . but why it doesnt, i dunno.

[color=blue][b]Yes! the structural strength of the coil keep the shape intact.
in addition, if students can explain why real Dc motor are with a iron core to strengthen the B field as well as provide the material of the coils to remain its shape. [/b][/color]

Page 7. Explore Activity B. Do they have to design experiments for all 3 parts? How much to design? Seems no need to write, but simply just rotate among the variables given as independent variables? How much time would that entail?
Page 7 Qn 13. Would the students know which "inquiry learning" you are refering to?

[color=blue][b]so long as it takes for student to explore meaningfully as productive activity, teacher need to support the weaker groups?
inquiry learning is a standard word in MOE science curriculum framework [img]http://www.woodgrovesec.moe.edu.sg/wbn/slot/u2357/Curriculum%20Innovation/MOE%20Sci%20Framework.jpg[/img]
http://www.moe.gov.sg/education/syllabuses/sciences/files/science-lower-secondary-2008.pdf page 1
should be fine :)[/b][/color]

Page 8. Qn 15: "....by varying..." this i changed on my system.
Page 8. Extend problem. Graphs. There are redundant axis labels. Eg the first pair only refers to FBy rather than the indicated angle and TB. Can these be removed? On my system, i just cover the redundant ones with a rectangle.

[b][color=blue]agreed[/color][/b]

Page 9. Graphs, same problem as Page 8 graphs. Same solution.

[b][color=blue]agreed[/color][/b]

Page 10. Qn25. the angle cta . . . can change to some other symbol thats more angle-like? theta or alpha or something? I dunno the reason for the choice of "cta".

[color=blue][b]beta better? = ? i changed in my worksheet
it is intended not to cause confusion with the other typical symbols commonly used and the simulation already used ?, ?[/b][/color]

lastly, just a general comment that this worksheet requires more brains and thinking than i initially expected. Its probably because I'm too lazy to think through the entire worksheet properly, but just scanning through. Some answers are not immediately obvious to me.

[color=blue][b]that is a good observation, the learning is intended to be more thinking than memorization :) [/b][/color]