Notes on Genres - Causal Explanation

Function

To explain how something occurs or why such phenomenon happens. Usually it details the various stages and explains the causes for the relevant change(s) involved in an event.

Schematic Structure

Phenomenon Identification ^ Explanation Sequence ^ Conclusion

Examples

2012 DSE 1B Q3b, 2012 DSE 1B Q9a, 2013 DSE 1B Q3b(ii), 2013 DSE 1B Q10b

Common vocabulary and sentence patterns used in setting questions

Explain why ...... occurs
Account for ......
Give reasons for the occurrence of ...
What causes ......?
Explain how...

Genre Structure and language features

Schematic Structure	Contents and Functions	Language features
Phenomenon Identification	State clearly the things or phenomena to be explained by identifying the causes and effects.	Use "If..." and "when..." to bring out the condition and cause. Clause "the reason for..." always brings out the following explanation.
Explanation Sequence	Explain the various characteristics of things or accounts for the different reasons of the occurrence of the phenomena in paragraphs	Use words to express the cause and effect, such as "Because", "because of", "due to", "resulting in", "since", "caused by", "leading to", "thus", "hence", "so that"... etc.
Conclusion (optional)	Summarize the explanation	Conjunctions "Therefore", "Hence" and "Thus" always bring out the conclusion

Schematic Structure

Contents and Functions

Language features

Phenomenon Identification

State clearly the things or phenomena to be explained by identifying the causes and effects.

Use "If..." and "when..." to bring out the condition and cause.

Clause "the reason for..." always brings out the following explanation.

Explanation Sequence

Explain the various characteristics of things or accounts for the different reasons of the occurrence of the phenomena in paragraphs

Use words to express the cause and effect, such as "Because", "because of", "due to", "resulting in", "since", "caused by", "leading to", "thus", "hence", "so that"... etc.

Conclusion (optional)

Summarize the explanation

Conjunctions "Therefore", "Hence" and "Thus" always bring out the conclusion

Example of Causal Explanation writing [Source: HKEAA 2013 DSE 1B Q3b(ii)]

A lift car is going up with constant speed as shown in Figure 1. The upward force raising the lift car is provided by the cable wound on a drum which is driven by a motor. Another counterweight of similar mass of the lift car is installed at the other end of the cable. The counterweight always moves in the opposition direction of the lift car. Assume that there is no slipping between the cable and the drum. Explain the advantage of having the counterweight installed at the other end of the cable.

If the counterweight is installed, the required output power of the motor is smaller. The reason is as follows. If the counterweight is installed at the other end of the cable, it will reduce the turning force generated by the motor. Thus, the motor needs less force to move the lift car up as compared with that without counterweight. Therefore, the output power required from the motor is smaller.

Analysis of Causal Explanation writing

Schematic Structure	Text	Linguistic Features
Phenomenon Identification	If the counterweight is installed, the required output power of the motor is smaller. The reason is as follows.	Use "If" to bring out the cause. Clause "the reason is as follows..." brings out the following explanation.
Explanation Sequence 1	If the counterweight is installed at the other end of the cable, it will reduce the turning force generated by the motor.	Material process "reduce" describes the function of counterweight.
Explanation Sequence 2	Thus, the motor needs less force to move the lift car up as compared with that without counterweight.	Material process "needs less" describes the change of work done by the motor.
Conclusion	Therefore, the output power required from the motor is smaller.	Causal conjunction "therefore" brings out the result, identifies the phenomenon again and draws a conclusion.