# 01 Measurement

## Micrometer Screw Gauge – Self-Practice GeoGebra Applet

After completing the vernier calipers applet, I simply had to do a similar one for the micrometer. However, this was a lot more complex as the thimble’s numbers are supposed to be “rotating” rather than moving linearly. A lateral movement of the thimble had to be coupled with a vertical movement of the rotating scale, with the corresponding numbers on the scale constantly changing with each new problem.

Students will need to make readings when the spindle is closed and when open to measure an object before subtracting the zero error and keying in the answer for the actual measurement. The answer will be checked for accuracy, although not for the correct number of decimal places because I have not figured out a way to programme that check yet.

To access the applet in fullscreen, go to https://www.geogebra.org/m/qedrwymk. To embed into SLS, you may use this code:

<iframe scrolling="no" title="Micrometer with zero error" src="https://www.geogebra.org/material/iframe/id/qedrwymk/width/640/height/480/border/888888/sfsb/true/smb/false/stb/false/stbh/false/ai/false/asb/false/sri/false/rc/false/ld/false/sdz/false/ctl/false" width="640px" height="480px" style="border:0px;"> </iframe>

## Vernier Calipers – Self-Practice GeoGebra Applet

The aim of this applet is to help students who just learnt about zero errors in vernier calipers to get some practice of their own. Students just have to key in their answer into the textbox and they will know if they got it correct.

To modify later: an option to give the correct answer if the student asks for it.

I have not figured out how to ensure that the input is expressed in 2 decimal places, so if any expert is able to advise, I will be glad to try it out.

To access the applet in fullscreen, go to https://www.geogebra.org/m/jybrnwgp. Meanwhile, the applet is embeddable in SLS using the following iframe code.

<iframe scrolling="no" title="Vernier calipers with zero error" src="https://www.geogebra.org/material/iframe/id/jybrnwgp/width/640/height/480/border/888888/sfsb/true/smb/false/stb/false/stbh/false/ai/false/asb/false/sri/false/rc/false/ld/false/sdz/false/ctl/false" width="640px" height="480px" style="border:0px;"> </iframe>

Credits to Abdul Latiff for the original applet which I modified to add the zero error readings.

## Who Wants to be a Base Unit?

This is a game that I play with my classes in the beginning of the course after they have attended the first lecture on base units. It serves as an ice-breaker since this is usually when I first meet them, as well as a recap of what they have learnt.

The rules are stated in the slideshow.

1. Each student is assigned a base unit out of 3 possible ones, kg, m, s. Note that the other 4 base units, A, mol, K and cd are not given because they will be covered in later topics.
2. For a class of 25, the following distribution is recommended:
a. kg – 5
b. m – 10
c. s – 10
3. Students will be asked to form groups when shown a Physical Quantity. Those with a negative power, e.g. the two “seconds” in kg m s–2, will have to sit/squat down.
4. Students who did not form a group will be ousted and the last few left in the game will win prizes.