A-Level Computer Science Introduction

Computational thinking Thinking abstractly, thinking ahead, thinking procedurally, thinking logically & thinking concurrently How to use this resource Presenting these exercises as a PowerPoint presentation allows you to use the resource in a variety of ways: Projecting the exercise from the front of the class as a starter/plenary activity. Printing out 3/6 slides per page to use as revision cards or a paired activity. Carousel activity with different groups looking at different scenarios, moving between groups, adding more ideas. Show the students the scenario. Using the computational thinking placemat as a handy reference. Students complete the activity on the card. The second slide in each scenario shows a typical answer. This is not exhaustive, and students may be able to elaborate further, beyond the points raised. The teacher can also pose follow up questions, with reference to the placemat to aid revision, e.g. “what are the advantages of this approach?”

Computational thinking Thinking logically Air France flight 447 On 1st June 2009, Air France flight 447 left Rio de Janeiro heading to Paris. It was a routine international flight. In the early hours of the morning, over the Atlantic Ocean, contact was lost, and the aeroplane vanished. On investigation, the plane showed signs of a high-speed impact with water as the nose cone was flattened. This ruled out a bomb or structural break-up. It was determined that the plane crashed into the water due to pilot error. The plane flew through a thunderstorm. Other aeroplanes had diverted that night, as is standard practice in bad weather. The pitot tubes (speed sensors) had frozen over as a result. This caused the autopilot to switch off and incorrect readings to be sent to the cockpit. This is expected behaviour, and pilots are trained to recognise this. Believing that the plane was losing altitude, the pilot pulled back on the stick to raise the nose, in an attempt to gain height. The instruments continued to show the plane falling. If an aircraft’s nose is pointed up too far, it loses speed, causing the engines to stall. The correct action is to point the nose down, gaining speed, before levelling off. With the aid of a flowchart, show how logical thinking could have avoided this accident. Thinking Abstractly Thinking Ahead Thinking Procedurally Thinking Logically Thinking Concurrently

Computational thinking Thinking logically Air France flight 447 Losing altitude? No Flowchart can be extended to include levelling off after pointing the nose up/down, so it does not crash! Yes Is there a thunderstorm ahead? Point nose up Is the plane stalling? No Yes No Divert plane to new heading to avoid storm Continue current course Yes Point nose down Thinking Abstractly Thinking Ahead Thinking Procedurally Thinking Logically Thinking Concurrently

Computational thinking Thinking procedurally and concurrently Cup of coffee Consider how a typical instant cup of coffee with milk and sugar is made. Think procedurally to break this process down into a number of smaller sub-problems. Think concurrently to identify which processes can be done simultaneously. Outline the reasons why some of the processes can and should be done concurrently, and those that can’t. Thinking Abstractly Thinking Ahead Thinking Procedurally Thinking Logically Thinking Concurrently

Computational thinking Thinking procedurally and concurrently Cup of coffee Prepare water Add water to kettle Boil water Add water to cup Prepare cup Add coffee to cup Add sugar to cup Add milk to cup Cup of coffee Students could also supply in the form of a flow diagram showing choices and decisions such as “Add Milk?” or “Add Sugar?” Try to tease out the idea of thinking concurrently. In this example it is clear that the cup of coffee with sugar and milk can be prepared while waiting for the water to boil. Thinking Abstractly Thinking Ahead Thinking Procedurally Thinking Logically Thinking Concurrently

Computational thinking Thinking abstractly, thinking ahead and thinking logically Taxi driver A taxi driver uses his experience, a GPS navigation system and radio tuned to traffic information to work out how to get passengers from A to B. In what ways is the taxi driver able to: Think abstractly Think ahead Think logically Thinking Abstractly Thinking Ahead Thinking Procedurally Thinking Logically Thinking Concurrently

Computational thinking Thinking abstractly, thinking ahead and thinking logically Taxi driver Possible answers to the challenge: Thinking abstractly: using road names, road labels, traffic indicators, speed indicator, estimated arrival time on his GPS system to filter appropriate information. Awareness of black spots from accident data. Thinking ahead: making sure there is enough fuel, planning a route to avoid closed roads. Thinking logically: making decisions when arriving at a junction/crossroads to take a correct turning, making decisions based on traffic ahead. Thinking Abstractly Thinking Ahead Thinking Procedurally Thinking Logically Thinking Concurrently

Computational thinking Thinking ahead New Horizons In July 2015, New Horizons, a space probe completed a fly-by of the dwarf planet, Pluto. In order for the mission to be a success, the team at NASA had to think ahead considerably in preparation for the mission before it launched in 2006. Research this mission, and compile a list of ways in which NASA had to think ahead. Thinking Abstractly Thinking Ahead Thinking Procedurally Thinking Logically Thinking Concurrently

Computational thinking Thinking ahead New Horizons Possible answers to the challenge: Calculating how long it would take to reach Pluto Calculating where Pluto would be in it’s orbit for successful arrival. Calculating the necessary speed, and gravitational assists required to reach the destination at the correct time. Planning for trajectory corrections, and having sufficient fuel. Planning what scientific instruments would be needed/could be carried/could be built in the timescales. Planning how to communicate with a probe with a 4 ½ hour time delay, when it can only do either scientific observation or communication at one time due to orientation. Planning for potential unknowns, e.g. trajectory to collide with unknown moon/ice debris. Whether this is a flyby or orbit mission. Flyby reduces the time available for scientific data to be gathered, but requires less fuel and therefore, less weight. Possible further missions to Kuiper Belt objects. Thinking Abstractly Thinking Ahead Thinking Procedurally Thinking Logically Thinking Concurrently

Computational thinking Thinking logically Cash point problem Thinking logically outline an algorithm which covers the situation of a user withdrawing cash from a cash point: Present your answer in either the form of: a flow-chart or pseudo code Thinking Abstractly Thinking Ahead Thinking Procedurally Thinking Logically Thinking Concurrently

Computational thinking Thinking logically Cash point problem Start Update balance Input card number Is it the correct PIN For this Card? Input PIN OUTPUT “Wrong PIN” Input amount to withdraw Enough Funds? Dispense cash Stop “Sorry” No Yes BEGIN INPUT CardNumber REPEAT INPUT PIN IF PIN is wrong for this CardNumber THEN OUTPUT “Wrong PIN” END IF UNTIL PIN is correct INPUT Amount IF there are enough funds THEN Dispense Cash Update customer’s balance ELSE OUTPUT “Sorry, insufficient funds” END Flowchart can be extended to include a PIN number only being allowed to be entered incorrectly up to three times before the card is retained. This could be done with a counter and a further check on the counter. Thinking Abstractly Thinking Ahead Thinking Procedurally Thinking Logically Thinking Concurrently

Computational thinking Thinking abstractly Maps and Abstraction Consider the tourist map on the right of city of Manchester. How has abstraction been used in the production of this map? Thinking Abstractly Thinking Ahead Thinking Procedurally Thinking Logically Thinking Concurrently

Computational thinking Thinking abstractly Maps and Abstraction Areas of the city have been colour coded Road name labels have been added Picture icons of various attractions have been added Key locations have been labelled with a circled number A key has been added with icons for key building such as car parks and post offices Major ring roads and the river have been coloured differently to clearly stand out Thinking Abstractly Thinking Ahead Thinking Procedurally Thinking Logically Thinking Concurrently