2.1 Elements of Computational thinking

The nature of abstraction The need for abstraction 2.1.1 Thinking abstractly The nature of abstraction The need for abstraction The difference between an abstraction and reality Devise an abstraction model for a variety of situations

Identify the inputs and outputs for a given situation 2.1.2 Thinking ahead Identify the inputs and outputs for a given situation Determine the preconditions for devising a solution to a problem The need for reusable program components

2.1.3 Thinking procedurally Identify the components of a problem Identify the components of a solution to a problem Determine he order of the steps needed to solve a problem Identify sub-procedures necessary to solve a problem

Identify the point in a solution where a decision has to be taken 2.1.4 Thinking logically Identify the point in a solution where a decision has to be taken Determine the logical conditions that affect the outcome of a decision Determine how decision affect flow through a program

2.1.1 Thinking abstractly Abstraction is the ability to filter the details that we do not need out of a problem so that we can create a more general idea of what the problem is. We may then be able to go on and apply the same problem solving procedure to other problems.

FOR INSTANCE, you could give a list of each London underground station and which other stations they are connected to, or you could produce a map like the London Underground tube map that abstracts the problem, making it easier to understand. Since this was so famous, this is now a common ‘template’ to use for other underground mapping systems

We noted that all cats have general characteristics, which are common to all cats, eg eyes, a tail, fur, a liking for fish and the ability to make meowing sounds. In addition, each cat has specific characteristics, such as black fur, a long tail, green eyes, a love of salmon, and a loud meow. These details are known as specifics.

Why is abstraction important? Abstraction allows us to create a general idea of what the problem is and how to solve it. The process instructs us to remove all specific detail, and any patterns that will not help us solve our problem. This helps us form our idea of the problem. This idea is known as a ‘model’. If we don’t abstract we may end up with the wrong solution to the problem we are trying to solve. With our cat example, if we didn’t abstract we might think that all cats have long tails and short fur. Having abstracted, we know that although cats have tails and fur, not all tails are long and not all fur is short. In this case, abstraction has helped us to form a clearer model of a cat.

Confusion: Activity 1 Come up with a system to help new students to find their way around the Rosedale Hewens Academy Trust

Activity 2: Representation of circle using below numbers

Activity 3: 8 kinds of fish, some eat others: Shark : {Kipper, Minnow, Piranha} Kipper: {Goldfish} Minnow: {} Tuna: {Minnow} Salmon: {Minnow, Tuna} Piranha : {Tuna, Kipper, Salmon, Minnow} Goldfish: {} Swordfish: {Minnow, Tuna} How would I work out a safe set of fish tank allocations so no fish was another's dinner? Other problems like this?

Discussion and Conclusion Method for solving a problem an algorithm – series of steps… computer can do this kind of rote work Graph colouring as a problem and a way of solving the graph colouring problem Problem Abstraction Removed details from the problem Represented it in a way that we know how to solve – here, as a graph Key Computing Science techniques find a common representation of a problem an algorithm to solve problems so represented learn to transform other problems into this representation Did you notice? This was brain work – no computer could do this

Solution In mobile systems, Freq 1 Freq 2 In mobile systems, each mobile mast has a short range reuse of frequencies is necessary but problematic How to ensure reuse doesn't cause interference? Use your knowledge for Activity 1 to solve the problem on Worksheet 2 Freq 1 Ask the pupils if they can identify how you might use the methods they saw in the first task to try and solve the following problem: Using the table on worksheet 2 pupils have to try to work out which base stations can reuse the same frequencies and answer the following question: - How many frequencies does the company need to buy?