revision for computer science

revision for computer science

1. Computational Thinking

   • Abstraction
     • Abstraction is a computational thinking technique that simplifies a problem by removing unnecessary detail so that you can focus on the important parts that are relevant to the problem.
     • the purpose of abstraction is to make it simpler so you can focus on the important parts.
     • The London Underground map is a classic example of abstraction. It focuses on the important details such as the station names and the routes from one to another along the various train lines.
     • Icons in a WIMP GUI
       • Icons represent programs and files within the UI. The actual programs and files are binary data stored as electrical or magnetic charges on secondary storage. When we double-click an icon to open it we give a command to the OS to load that binary data into memory. When we drag-and-drop an icon to move it from one folder to another the OS manages the physical movement of data on the disk
   • Decomposition
     • Decomposition means breaking down a complex problem into smaller, more manageable parts.
       • Each smaller part can then be solved individually.
     • Decomposition allows large teams to each take a part of a problem and work on it.
     • Structure charts
       • Structure charts are used to break a large program down into the smaller parts that make it up. Each box represents a smaller problem to be solved. The lines show which bigger problem each box is a part of. Structure charts are a very useful tool when designing a solution to a big problem, such as a creating a computer game.
   • Computational thinking is a way of understanding complex problems in order to form a solution that can be implemented by either a computer, a human or a combination of both.
   • Algorithmic Thinking
     • Algorithmic thinking is a way of solving a problem by producing algorithms.
     • Algorithms can be written as a set of numbered steps to follow such as a cooking recipe or assembly instructions, however in computing they are presented as pseudocode or flow diagrams.
     • algorithm building blocks...Sequence - a series of steps that are to be completed one-by-one. Selection - steps that only occur if a certain condition is met. Iteration - steps that repeat, either for a fixed number of times or until a condition is met. We use each of these algorithm structures when programming.