P6 Science Question on Light Bulb

This picture has been making its way around the internet. This is a Primary 6 Science question that has a questionable answer. As teachers, there are times when we make mistakes in crafting answers for a multiple-choice question. Good thing there is often a fail-safe in the form of our colleagues who would help each other vet the questions we set. Sometimes, despite all effort, mistakes are made such as this

Primary 6 Science Question on Light Bulb

The story according to the person who posted this:

This P6 science question is taken from a paper that is set by a local brand name primary school. The majority of the students who took this test gave the answer as (4). The science teacher insisted that the answer is (2). The reason given was that sentence D should be interpreted to mean that only light energy is given off when an electric current passes through it.

The children, as well as many other adults who are well versed in the English language, unanimously agreed that the students were correct to interpret the sentence as meaning that the bulb will give off light energy (though it does not rule out other forms of energy) only if an electric current passes through it (so if there is no electric current, the bulb will not give off light energy.

The HOD called to clarify that her teacher (and therefore the dept) is correct. She apparently said that there is nothing wrong with the statement, and that it is not meant to be read in an 'English' way, but rather in a 'scientific' way. She then proceeded to read the sentence aloud, pausing after the word 'only'. When it was pointed out to her that there is a need for a comma after 'only' if it is to be read with a pause, she insisted that that was the 'scientific' way of reading the sentence, and went on to qualify that laymen would not be able to distinguish between the scientific reading and the English reading, but that the students, having studied the subject for four years, were expected to tell the difference. According to her, this would set the A* students apart from the A students.

Since when our English language developed a 'scientific' dialect?! And if you cannot apply standard English language rules to reading the questions of a paper set in English, then perhaps we need to clarify that the paper is written in Scientific-English instead? What kind of nonsense is this?

Many netizens have condemned the answer which was given by the teacher as (2) instead of (4), what made matters worse was the defence given by the HOD. I agree that the statement D could be better phrased as "It gives off only light energy when an electric current passes through it", therefore making it a false statement and hence, not part of the answer.

This incident reminds us of the need to be careful in the way we phrase our questions, often re-reading them to see if they could be misinterpreted or if they could be made clearer.

Make Your Own Comic Strip for Teaching!

A concept cartoon is an innovative way of eliciting discussions about science concepts. For example, it can present differing views on a scientific phenomenon from different characters.

I am not an artist but do wish sometimes that I could make classroom discussions more interesting by using relevant cartoons or comic strips. Then I stumbled upon some websites that enable you to create your own comic strips using readily drawn characters and images. The characters have a number of common facial expressions, which makes the story-telling fun. You may even add on your own colours or drawings such as backgrounds and other objects later on after you have downloaded the soft copy of the image for the strip that you have made.

Do try out http://www.makebeliefscomix.com/Comix/ where I made a strip as a trial. I certainly hope to get more ideas for teaching in future where this will come in handy.

Free Concept Cartoon Generators

How to survive a lightning strike

This is an interesting question on electricity: in order to survive a lightning strike, which of the following costumes offer the best protection? A coat of armour, your birthday suit, a wetsuit or a superman costume? Watch this MinuteEarth video on Faraday's cage to find out!

18 Must-Have Items for a Physics Teacher

Many a science teacher would have wanted to conduct a demonstration at the last minute but could not do so due to a lack of equipment or material. I have experienced that many times and even though I have many of these items hidden somewhere in some drawer, I can never seem to be able to find them.

So here is a list of items that I intend to pack into a toolbox for any teaching emergency.

Adhesive tape
Copper wire (bare)
Copper wire (insulated)
Pair of wires with crocodile clips
3 Neodymium magnets
6 ball bearings
1 PVC tube
1 PVC track
3 pendulum bobs
Box of paper clips
3 balloons
2 candles
Aluminium can
Plastic bottle


Electromagnetism Lecture

I enjoy lecturing on topics like Superposition and Electromagnetism in the GCE A-level syllabus as they lend themselves well to the use of fun demonstrations that I can perform in front of the audience.

One of the recent demonstrations that I did was to demonstrate the measurement of the magnetic force acting on a wire and to show that the force can be inverted when the current is reversed. The magnitude of the force can be shown to be consistent with the relationship F = BIl sin theta, where B is the magnetic flux density, I is the current within the wire, l is the length of the wire and theta is the angle between the wire and the magnetic field. This can be illustrated by independently varying one of the 4 variables and observing the change in force.

The setup is also a good for a demonstration to illustrate Fleming's Left-Hand Rule.

For more details, visit http://www.scienses.com/measuring-the-force-on-a-current-carrying-conductor/.

Meanwhile, here's a video I made to show what I did:

Thorium as an alternative source of nuclear energy

It's about time Singapore considered building a liquid fluoride thorium reactor as a safe source of nuclear energy. From the video, it would appear that thorium is safe as it cannot be weaponized, does not require high pressure containers and the risk of a meltdown does not exist. For a small island state like Singapore, this presents an attractive way of obtaining relatively clean abundant energy. I'm sure if we think hard enough we will be able to solve the other problems such as storage of waste products.

Perhaps the part of our syllabus on Nuclear Physics will need to be updated then.

Siphoning water

This video is taken during my IP4 class today. My students are making use of rubber tubes to demonstrate how we can use gravity to siphon water from one place to another. As long as the level of the source is higher than the level of the receiving end, we can do so.

Angular Displacement - 2011 A-level question

A disc rotates clockwise about its centre O until point P has moved to point Q, such that OP equals the length of the straight line PQ. What is the angular displacement of OQ relative to OP?

A.   \frac{\pi}{3} rad

B.   \frac{2\pi}{3} rad

C.   \frac{4\pi}{3} rad

D.   \frac{5\pi}{3} rad

Static Electricity

image source: http://www.sxc.hu/photo/243992

This question is meant for TA 2B and 2C Physics students.

Other than the demonstrations we have tried out during class, could you think of any other way in which static electricity can be observed?

Please leave your comments below. You may need to log in to Facebook while doing so.