Friday, 22 July 2016

From unplugged to programming

Modem was high and low sound - now we use light.

We send all our information to America via a cable under the ocean - in programming - on and off, high & low, white & black light, Red and blue etc. IT is in frequencies but looks like different colours - using LEDs.

The unplugged things we have been doing - we were doing 20 years ago e.g. binary numbers etc. The information and technology is still the same. The applications for the technology will change but the basics behind it all stay the same.

Scratch did not exist but all the elements of Scratch did exist. Alan Turing - cracked the Enigma code by unpacking the basic elements of the programme:

Every programme needs these things...
(SCRATCH - where does it fit?)

1. Receive input (ASK)
2. Send output (SAY)
3. Store data (VARIABLE - data)
4. Sequence (The blocks)
5. Iterate or repeat (REPEAT)
6. Make a selection or decision (IF - THEN)

You might not need all of these elements but like music - a song is not quite right without pitch or rhythm.

Bebots - mostly look at sequence.
We can teach these things unplugged.

Scratch Junior iteration and output but not the other elements.
Scratch - all elements.

Shopping has changed!
In the past we totalled up prices on a piece of brown paper.... the computer does it now.

How do barcodes work?
Every 2nd number added, every other number added up then bottom number x 3 then subtract top number.

If the scanner is incorrect - the computer flags up an error - Check Sum.
9 x 3 = 27 (7)

9 1 8 8 7 2      10, 8, 6, 3, 5
3 2 2 5 1 7                        0                                         (Clock multiplication)
1. Add them all up - but only focus on the last digit. (Function in scratch = Mod 10)
2. Take 0 x 3 = 0  5 + ? = 0 1 in 10 chance to get it correct

You might read out an incorrect number or swap two when typing it into the checkout machine. Test this on your sequence of numbers from the bottle of water - how does it change the answer?

Where else might humans make mistakes?

Binary Tables:
Computers only work on 0 or 1. They need you to be very precise.

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