Irish Leaving Certificate Computer Science

Computational thinking is a way of solving problems so that the solution can be carried out by a computer, or by a person following the same steps exactly. It is not programming itself. It is the thinking that comes first, and a program is one way of writing the result down. The same thinking is used when planning a timetable, sorting post or working out the quickest route through a city. ## A systematic process for solving problems A systematic process is one that can be described, repeated and checked, so two people following it reach the same answer. Computational thinking usually works through these stages. 1. State the problem precisely: what is given (the inputs), what must be produced (the outputs) and what conditions apply. 2. Break the problem into smaller problems that can each be solved on their own. 3. Look for patterns, including similarities with problems already solved. 4. Decide what detail matters and ignore the rest. 5. Write the steps of a solution as an algorithm. 6. Test the algorithm on examples, including awkward ones, and improve it. The stages are not passed through once. A test in the last step often shows that the problem was stated loosely, so the work returns to an earlier stage. Solving a problem in this repeated way is called an iterative approach. ## Decomposition **Decomposition** means breaking a problem into smaller units, each simple enough to solve and to test by itself. The smaller units are then combined. Decomposing again at each…