Primary Mathematics

Modelling Approach

The example of a moelling questios and solution

1) The part-whole model
We use this model on problems which :
a) requires us to fin the whole give both parts of a quantity

<-------------------?--------------->
__________________________
| known | known |

b) require us to find out one part of a quantity given the whole and another part of the quantity

<-----------------known------------>
___________________________
| known | ? |


2 The comparison model
This model shows the relationship between 2 quantities. We use this model on problem which :
a) involve a difference between two quantities

A : ______________________
| |

B : ________
| | <------difference->

b) involve a ratio between 2 quantities

A: __________________
| | | |
<-------3 units--------->
B : _____
| |
<--1 unit

3) The 'change' model
This model shows the relation between the new value and the original value of a quantity

Before : _____________________
| |

After ______________________________
| | Addition |

Other technique that can be applied other than modelling are guess and check, making a systematic list, etc, could be used.


Example of a question and solutions :
Eric is 10 and his mother is 42. In how nmany years ' time will his mother be 3 times as old as him ?

Solution
At present :
Eric's age ________
| 10 years |<------ difference 32-->
Mother's age _________________________
| 42 years |

Some years later
Eric's age _________________
| 10 years | some years|<------ difference 32-->
<-------1 unit----------->

Mother's age __________________________________
| 42 years | some years|
<-------- 3 units ------------------------------->

So, 3 units - 1 unit = 32 years
2 units = 32 years
1 unit = 16 years
Hence, in (16-10) years, which is 6 years time, Eric's father will be 3 times as old as him



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posted by Blogs @ 2:43 AM