Week 16 · Theme 3 Digital Citizenship, Lesson 1 Explorer in Action · 3 lessons
1
Learning from examples: training a computer
ICT P6 Term 2, Theme 3: pp. 8–13
GoalExplain how a computer learns patterns from labelled examples, and what an algorithm is.
New words
algorithm · step-by-step instructions for solving a problemmachine learning · a way for computers to learn patterns from examplesdata · the information a computer uses, such as pictures, sound, video or textblockchain · a digital record kept on many computers at once, so one person cannot quietly change it
Explanation
Voice helpers can answer you by voice. They learn from what people teach them, and they use data kept in the cloud. How does a computer learn? It is shown many examples, and each example has a label. The examples can be pictures, sound, video or text. The computer looks for patterns, things that repeat. After enough labelled kites and labelled balls, it can guess whether a new picture is a kite or a ball. This is called machine learning. An algorithm is a list of step-by-step instructions for solving a problem, like the steps of a recipe. A tool can be designed by pairing an algorithm with some data. One more word: a blockchain is a digital record kept on many computers at the same time, so one person cannot quietly change it. In this lesson you will play the computer yourself, with paper cards and no device.
many labelled examples→computer finds patterns→it can sort a new picture
Worked examples
Label
Pattern the computer notices
kite
diamond shape, tail, string
ball
round shape
Seif plays the trainer. He shows his classmate, who plays the computer, ten cards: five labelled kite, five labelled ball. The kites have a diamond shape, a tail and a string; the balls are round. When Seif shows a new card with a diamond shape and a tail, the ‘computer’ says ‘kite’.
pick up a card→look at its shape→round: pile A, not round: pile B→repeat
An algorithm for sorting the cards has steps: pick up a card; look at its shape; if it is round, put it in pile A, if not, put it in pile B; repeat until no cards are left. The steps are in order, and the order matters.
A card game. Mariam draws one algorithm card (the steps for sorting) and one data card (pictures of fruit). Together they make a tool idea: a fruit sorter.
Class activity
Be the computer. In pairs, make twelve small picture cards of two kinds of things you can draw easily, such as kites and balls. The trainer shows eight labelled cards to the ‘computer’. Then the trainer shows four new cards without labels. The ‘computer’ sorts them into two piles and says which pattern it used. Swap roles. Write: what pattern did you use?
Practice
1
Name the kinds of data a machine can learn from.
Images, sound, video and text.
2
What is an algorithm?
Step-by-step instructions for solving a problem.
3
What does machine learning find in the examples it is shown?
Patterns, things that repeat.
4
What is a blockchain, in one sentence?
A digital record kept on many computers at once, so one person cannot quietly change it.
