Lesson: efficiency of algorithms

The lesson is suitable for GCSE / KS3 Computer Science (see other similar lessons in this series)

• To understand that more than one algorithm can be used to solve the same problem.
• To compare the efficiency of algorithms explaining how some algorithms are more efficient in solving algorithms than others, specifically space and time efficiency of algorithms

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• Lesson plan
• Presentation on space efficiency that looks at a simple algorithm of adding up consecutive numbers (eg 1 + 2 + 3 + 4 … ) in a sequence, then compares this approach with using a loop and then looks at using an equation to solve the problem as an example of space efficiency in an algorithm.
• Pupils program these algorithms for themselves to see how lines of code can be reduced in a program.
• The above presentation is supported by three python programs (eg sequence, loop, equation python programs)
• Presentation on time efficiency that looks at two algorithms (one using a loop and another using an equation) to see which ones are more time efficient.
• Pupils program these algorithms to see how execution time of a program can be reduced.
• The above presentation is supported by two python programs (eg loop and equation python programs)
• The pupils are then given a program task to try to create a program that will calculate the nth term of the sequence 2, 4, 8, 16 in the most efficient way.
• A stretch and challenge exercise considers how to program a more difficult sequence of numbers
• Plenary presentation quiz to test pupils knowledge
• Homework looking at definitions of space and time efficiency and an example algorithm (answers provided)