1. Top-down technique / Stepwise Refinement and Algorithms
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2. Learning Objectives:
Explain the top down approach to problem solving / Stepwise Refinement .
Turn a:
Problem into a mathematical formula.
Problem into a series of stages (algorithm).
Algorithm into a flow diagram.
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3. Top-Down Technique / Stepwise Refinement
A problem solving technique:
The problem is divided up into a number of smaller problems called modules.
Each one is solved separately.
Then each module is combined to form a solution to the whole problem.
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4. Algorithm An explained solution to a problem.
There are a number of ways of presenting algorithms.
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5. How do we find the area of a 'house' made up from a square and a triangle?
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6. Prose (language description) / / Structured English
Find the area of the triangle by multiplying the base by the height and halving. Find the area of the rectangle by multiplying the width by the breadth. Then add the area of the triangle and rectangle together.
Each sentence is a module.
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7. Formulae Each formula is a module. AT = ½ BH AR = W + H + W + H
BT = Base of the triangle
HT = Height of the triangle
W = Width of rectangle
BR = Breadth of rectangle
AT = Area of the triangle
AR = Area of the rectangle
AT = ½ BH
AR = W + H + W + H
= 2 * (H + W)
Area of the house = AT + AR
Each formula is a module.
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8. Ordered Steps / Structured English
Find the height and base of the triangle.
Find the area of the triangle by multiplying the height of the triangle by the base of the triangle, and halving.
Find the width and breadth of the rectangle.
Find the area of the rectangle by adding the width of the rectangle to the breadth of the rectangle, and multiplying by 2.
Add the areas of the triangle and rectangle together.
Each step is a module.
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9. Flowchart
Ordered steps using arrows to point from one instruction to the next instead of numbers.
Find the height and base of the triangle.
Find the area of the triangle by multiplying the height of the triangle by the base of the triangle, and halving.
Find the width and breadth of the rectangle.
Find the area of the rectangle by adding the width of the rectangle to the breadth of the rectangle, and multiplying by 2.
Add the areas of the triangle and rectangle together.
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10. Plenary
Explain the top-down approach to problem solving / Stepwise Refinement .
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11. Top-Down Technique / Stepwise Refinement
A problem solving technique:
The problem is divided up into a number of smaller problems.
Each one is solved separately.
Then each one is combined to form a solution to the whole problem.
20/06/2019