Tell students:
We use shortcuts all the time in daily life: a common example is in texting.
Popular abbreviations can speed up communication, and with no loss of meaning for those who are familiar with them
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Extension activity Alternative for Engagement and Expression: If you think students might struggle with this task, you could do (or start with) the classic ‘telephone game’, also known as ‘Chinese whispers’, with which students should be familiar. |
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Working memory Alternative for Engagement and Expression: You could use an online quiz program such as Quizlet or Kahoot!. Ask students to guess the answers. Alternatively students devise their own quiz questions and answers. |
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Working memory As a means for Engagement and Expression: An alternative to the scrabbled message can be to focus on one word or a phrase for example using the game hangman where certain letters are missing or students have a number of guesses to work out the word or phrase. |
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Working memory As a means for Engagement and Expression: For students who may struggle with a sentence focus on single words to start with. |
Compression techniques are needed to reduce the size of data transmissions. This lesson examines techniques that achieve this.
One category results in a loss of data but still retains sufficient data to convey the message (such as an image, audio or video) whereas the other can restore all original data following transmission. These two approaches are known as lossy and lossless compression respectively.
Introduce ‘lossless’ compression as used by Portable Network Graphics (PNG). This is achieved using a combination of Huffman and LZW (the initials of the three inventors) compression algorithms and involves two steps:
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Additional scaffolding As a means for Expression: An alternative task is to focus on a text with which they are more familiar. Ask them to compress one of their favourite stories such as ‘The Three Little Pigs’ (e.g. “Who can write the story in the fewest words possible?”) They could retell the story to a younger student. |
Have students submit a one-page report, including image screenshots, to explain and evaluate lossy and lossless image compression techniques.