O-level English : There is no point in preserving the past. We should be looking to the future.

Sample Essay

http://mareingenii.t15.org/EngOlvl/There%20is%20no%20point%20in%20preserving%20the%20past%20We%20should%20be%20looking%20to%20the%20future.html

Polarized Light Microscopy

A student of mine tore apart his old digital dictionary that he was going to toss in the trash. We had a nice time discussing its construction and he gave me its LCD screen from which I tore off a polarizing film. I cut the film into discs and added them to the light path of my Olympus CHB microscope. One went under the eyepiece turret while the other under the condenser.

These are the results:
Citric Acid Crystals at 100 times magnification (Camera : LG Optimus Black)

Small Citric Acid Crystal at 400 times magnification  

A technical treatment of this is available here:
http://www.microscopyu.com/articles/polarized/polarizedintro.html

Math : Problem Sum

PSLE math : Primary 5 problem sum.
THis is a post in response to a question from one of my students.

This app is so Awesome!

http://www.scaleoftheuniverse.com/

Physics : Motion in a vertical circle

My handwritten Physics notes on motion in a vertical circle.

Japanese Sec 4 math question

Holy cow. I saw this sec 4 level question from a Japanese forum.
http://www.page.sannet.ne.jp/ikenoue/type2/area/area.html

Apparently its for some entrance exam.

I think the Japs are insane...
My solution provided. The solution on the webpage is different from mine because they
defined the radius of the circle as half r while I defined it as r, but basically the same strategy.

Physics : Lissajous Figures

Ever since I first read of them in junior college, I have always found Lissajous figures mesmerizing and beautiful.
I found a simple way to create them without using two function generators (poor me; I could only afford one) by using the left and right audio channels of a laptop.

You can also create them in sand! This is a hands-on experiment I did at a science camp; needless to say, the kids loved messing around with it.

Physics : Corner cube reflectors

This is a corner reflector used by surveyors to measure distances precisely by bouncing lasers off them. [Link to Wikipedia article]. Read up on how they work; their operation is relevant to total internal reflection and prisms in O&A-level physics.

This particular reflector was near a bar named "The Colonial" above Little India Station on the underground NEL line. They can also be found on almost all the pillars that support the elevated sections of old East-west and North-south MRT lines.

The coolest thing about these reflectors is that the Apollo astronauts left a panel of them on the moon. [Link to Wikipedia Article] I really think it is ridiculous that anyone should doubt that men have been to the moon, especially when observatories around the world bounce lasers off those reflectors to measure the distance to the moon. Don't try using your laser pointers; the power needed to reach the moon is in the neighbourhood of a hundred watts, and even then, only a few photons get reflected by the corner reflectors and make it back to earth!

Chemistry : Air conditioner refrigerant fluids

This is a photograph of a tank of refrigerant fluid used by a repairman to recharge old air conditioners and refrigerators.

The liquified gas in the tank is Chlorodifluoromethane [Link to wikipedia article] which is a formed by allowing chlorine and fluorine atoms to replace hydrogen atoms in the methane molecule in a textbook reaction known as substitution.

GP Essay : The language of mathematics is the perfect language. Do you agree?

This essay topic is not an easy one to write on.
A student of mine posed this topic to me as a friendly challenge which I was glad to take on.
I might not have done as great a job on this as I would have liked but this represents my best efforts.
I was not time constrained; I took about 4 hours to write this in two sittings.

Click here for the essay:
The language of mathematics is the perfect language. Do you agree?