HIGHER CS STANDARD ALGORITHMS Part 1- Ensuring fuller understanding of the basic concepts

Who am I? Principal Teacher of Computing at Crieff High School CAS Scotland committee member National Project Officer since August

Session Overview Importance of students developing a precise understanding - The problem with intuition - The hidden mechanism concept - Does this just apply to programming? Ways to assess and help secure pupils understanding of the basic concepts - Peer instruction - Identifying and describing hidden mechanisms

Current teaching of standard algorithms What approaches do you currently use or are planning to use? What approaches do you find work well? What would you like to improve?

Importance of developing mechanistic reasoning Relying on intuition vs understanding Concept of a hidden mechanism Does this just apply to programming?

Problems of prior pupil experience Intuition Reliance on the other persons experience and ability to deal with ambiguity. Precision doesn’t really matter Reliance on copying other examples that might be similar. “The computer doesn’t like me and is being awkward” Understanding Realisation that a computer has no prior experience and struggles with ambiguity. Precision is crucial Choosing features based on what you want the computer to do. “I haven’t correctly described the process”

What kind of understanding do they need? Awareness of structure and how different elements relate to one another Consistent model of how a process description is carried out by a computer or other person Static view of a particular instant in time that’s probably easier for novices Dynamic view of a series of actions unfolding over time and probably harder for novices

Does this just apply to programming? No Computing Science is an information structure and process orientated discipline Modern UI’s allow a try different things until it works approach

Peer instruction to test for faulty mental models Brief overview of PI PI questions for the audience Research evidence of its effectiveness

Peer Instruction Technique originally developed in Physics by Eric Mazur at Harvard university Way of assessing whether novices really understand concepts requiring a precise understanding Based on carefully designed multiple choice questions with structured discussion and voting

PI in a secondary school context Before Pupils have worked with the concepts in class or at home. Individual Pupils read the question and choose an answer Vote takes place Group Pupils discuss what answer they chose and why Vote takes place Class Teacher facilitated discussion Vote takes place Correct Answer Teacher reveals the correct answer Teacher explains why it’s correct

The variables angel and egyptian contain 1.7 and 2.0 respectively, which represent their height. What is written out…? IF angel > egyptian THEN SEND "Egyptian is taller" TO DISPLAY ELSE SEND "Angel is taller" TO DISPLAY END IF A.Egyptian is taller B.Angel is taller C.Egyptian is taller Angel is taller D.

Consider what this code does when metalColour is blue, red, or green… IF metalColour == "blue" THEN SEND "Cold" TO DISPLAY ELSE IF metalColour == "red" THEN SEND "Hot!" TO DISPLAY ELSE SEND "Try again!" TO DISPLAY END IF Which options are true? A.When metalColour is blue, Cold displayed B.When metalColour is red, Hot! displayed C.When metalColour is blue, both Cold AND Try again! displayed D.When metalColour is green, nothing happens

What is written out…? SET n TO 4 WHILE n > 0 LOOP SET n TO n – 1 END WHILE SEND n TO DISPLAY A.-1 B.0 C.1 D.2 E.3 F.4

How many times is Hello written out? SET i TO 0 WHILE i <= 5 DO SEND "Hello" TO DISPLAY SET i TO i + 1 END WHILE A: 4 B: 5 C: 6 D: 7 E:

How many times is Hello written out? SET i TO 10 REPEAT i TIMES SET i TO i – 2 SEND "Hello" TO DISPLAY END REPEAT A: 10 B: 8 C: 6 D: 4 E: 2 F: 0

PI vs teacher explanation Statistically significant effect Twice as effective as a good teacher explanation Successfully used in Physics, Maths and Computing Science Develops better sense of self efficacy particular amongst girls

Identifying and describing mechanisms The importance of CS speak Identifying mechanisms in a simple piece of code Activity involving identifying and describing mechanisms

Why the language matters Without CS speak you have -no way of clearly identifying the mechanisms -difficulty connecting the problem description to the code or features you need for the process description Forced to rely on showing them lots of problem descriptions and the code or steps to solve them.

CS Speak provides A common language to describe their understanding. Helps to transfer learning to another programming language. Helps transfer from one example to similar problems. However they need opportunities to practice using the language!

conditional repetition complex condition logical comparisons output Identifying and describing mechanisms assignment to a variable input SET password TO “” SET attempts TO 0 REPEAT SEND “Please enter the correct password” TO DISPLAY RECEIVE password FROM (STRING) KEYBOARD UNTIL password = “12345” OR attempts > 3

Identifying and describing mechanisms SET lotto_player TO [“”, ””, ””, ””] FOR player FROM 0 TO 2 DO SEND “Please enter players name” TO DISPLAY RECEIVE name FROM (STRING) KEYBOARD SET lotto_player[player] TO name END FOR selected = pick_random( 0, 2) SEND lotto_player[selected] & “has won!” TO DISPLAY

Key Challenges Code writing before code comprehension makes this more difficult for novices Need to understand the hidden mechanisms Computational constructs are tightly linked

Questions