Wednesday, November 23, 2011

Science: How to Answer Section B (I)

Science section B is the most difficult part in Science paper. You need to complete the section B within 30min. It carries 20 marks. In order to answer the section B well, you need to understand the pattern of the question and the keywords.
Here are thel keywords that you need to understand in section B:-
constant variables (variables that are kept the same), responding variable, manipulated variables (changed), aim (purpose), hypothesis (relationship), inference (reason) and conclusion.
Let us look at the differences between constant variable, responding variable and manipulated variable.
Constant variable, Responding variable, Manipulated variable
Constant variable: Does not change or varying. Sometimes they will use the term as 'keptconstant'
Responding variable: To act in return or in response to an external factor or the stimulation.
Manipulated variable: Controls individual factor causes. Another term used is 'changed'

Mnemonic Graph & Table analysis
When come to data analyzing, here are some mnemonics that can help you to figure out theresponding variable and manipulated variable from graphs and tables:
  1. Left Change Right Respond 左操右反
  2. Up Change Down Respond 上操下反
  3. Horizontal Change Vertical Respond 横操直反
and remember that Unchanged is constant (不动则固), to look for constant variable.

Left Change Right Respond

                             (Diagram 1)
                             (Table 1)
Diagram 1 shows an investigation of frictional force. Table 1 shows the result of the investigation.
Refering to table 1, the data on the left shows the types of surface to use in the investigation. It is controlled by the investigator and will affect the end results of the investigation. Thus,surface is manipulated (changed) variable 
The data on the right shows the distance travelled by a toy car. The changes is due to the surface used. Thus, the end results on the right column is depend on (respond to) the changes on left. Distance travelled by a toy car is responding variable.
What is the unchanged data? The height of the surface and the toy car. The student will use the same toy car and same height of the surface for every test. So, toy car and height areconstant variables.

Up Change Down Respond
It means the data on the upper part of the table is manipulated (changed) variable. The data at the bottom part of the table is responding variable
                                 (Table 2)
Ah Beng prepared 2 beakers which are filled with 300ml water. The water temperature used is 40Cº and 100Cº respectively. Ah Beng adds in 8 table spoons of sugar into each beaker and stirs until the sugar is fully dissolved. Table 2 shows the result of an investigation about the time taken to dissolve the sugar.
In this investigation, the water temperature is manipulated variable, because changes in the water temperature will affect the end result of the time taken for sugar to dissolve in water.
The data at the bottom (Time taken for sugar to dissolve) responds to the manipulated variables. The result depends on the temperature of the water.
Constant variable are beakers and water volume, because both tests are using the same bealer size and the same amount volume of water.

Horizontal Change Vertical Respond
The data on horizontal axis is manipulated (changed) variable. The data on the vertical axis is responding variable.

                                           (Diagram 2)
Diagram 2 shows a bar chart on the number of telephone numbers memorised by 5 people aged 25, 35, 45, 55 and 65 years.
In this investigation, the age is the manipulated variable. As the age changes, the number of telephone numbers could be memorised changes. The number of telephone numbers that can be memorised is responding variable. The result depends on the age of the person.
Constant variables are the numbers of telephone number and the time given to memorise the telephone numbers used in the investigation must be the same.