Algorithms

Abstraction is the representation of essential features without including unnecessary details.  It is used to reduce the complexity of systems for users, hiding how things actually work, applying algorithms to different contexts and producing suitable user interfaces.  The first video explains the concept at a level suitable for GCSE using the example of a sat-nav system.

Problem decomposition, or breaking a problem down is an essential skill to becoming an experienced programmer.  The second video explains the concept using an everyday example of crossing a road and also how it applies to simple games design.

The third video explores algorithmic thinking: getting to a solution by identifying the individual steps needed.  An algorithmic way of approaching a word-search is used as an example.  The code used is not important in this video, merely the approach of breaking a problem down to achieve a working solution.  Advantages algorithmic thinking are discussed in another video, “Decomposition”.

An alternative to the binary search, the linear search methodically checks each item in a list until the one you are looking for is found.  The fourth video introduces the algorithm.  It is usually less efficient than a binary search, unless the item you are looking for is towards the start of the list.

An alternative to a linear search, the binary search starts in the middle of a list and removes half of the items from the list until the item you are looking for is found.  It is usually more efficient than a linear search.  The fifth video introduces the algorithm.

The bubble sort is one of three sorting algorithms students need to know for GCSE exams.  The sixth video explains the bubble sort technique.

The merge sort is one of three sorting algorithms students need to know for GCSE exams.  The seventh video explains the merge sort technique.

The insertion sort is one of three sorting algorithms students need to know for GCSE exams.  The eighth video explains the insertion sort technique.

The ninth video explains two common methods of describing algorithms for problem decomposition: pseudocode and flow diagrams.  OCR have a very specific list of keywords they use for algorithms that can be found in their specification, and are outlined in this video.  The key flowchart symbols students can expect to see in exams are introduced.

Resources:

https://student.craigndave.org/videos/ocr-gcse-slr2-1-abstraction

https://student.craigndave.org/videos/ocr-gcse-slr2-1-decomposition

https://student.craigndave.org/videos/ocr-gcse-slr2-1-algorithmic-thinking

https://student.craigndave.org/videos/ocr-gcse-slr2-1-linear-search

https://student.craigndave.org/videos/ocr-gcse-slr2-1-binary-search

https://student.craigndave.org/videos/ocr-gcse-slr2-1-bubble-sort

https://student.craigndave.org/videos/ocr-gcse-slr2-1-merge-sort

https://student.craigndave.org/videos/ocr-gcse-slr2-1-insertion-sort

https://student.craigndave.org/videos/ocr-gcse-slr2-1-how-to-produce-algorithms

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This resource is part of Craig ’n’ Dave OCR GCSE Computer Science

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