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1. Technologies K–10 · Kindergarten

   A real-object graph: how we travelled to school today

   Data can be shown with objects: one cube for each child, stacked in the column for their answer, makes the most common answer the tallest column.

   PracticalLow risk

2. Technologies K–10 · Kindergarten

   Digital system or not: sorting classroom objects

   A digital system takes an input, follows instructions stored inside it and gives an output, so a tablet or a calculator is a digital system while a pencil, a wind-up timer or a torch with a plain on-off switch is not.

   PracticalLow risk

3. Technologies K–10 · Years 1–2

   Inside a digital kitchen scale: input, processing and output

   A digital kitchen scale is a digital system: a sensor feels the load (input), a chip turns it into a number (processing) and the display shows grams (output).

   PracticalLow risk

4. Technologies K–10 · Years 1–2

   Pictures from numbers: shading a pixel grid from a code

   A picture can be stored as rows of 0s and 1s, where each digit says whether one square (a pixel) is left white or shaded.

   Practical, model not builtLow risk

5. Technologies K–10 · Years 3–4

   Input, output or both: testing computer peripherals

   A peripheral is an input device if data goes from it into the computer, an output device if data comes out of the computer to it, and both if data goes both ways.

   PracticalLow risk

6. Technologies K–10 · Years 3–4

   One temperature log, three representations

   The same data can be represented as a table, a line graph or a colour scale, and each representation suits a different purpose.

   PracticalLow risk

7. Technologies K–10 · Years 5–6

   Binary cards: counting with on and off

   Five cards showing 1, 2, 4, 8 and 16 dots, each either face up (1) or face down (0), make every whole number from 0 to 31 in exactly one way, which is how digital systems store numbers as off and on states.

   Practical, model not builtLow risk

8. Technologies K–10 · Years 5–6

   Inside a desktop computer: naming the main components

   A computer's main internal components each have one job: the processor (CPU) follows instructions, memory (RAM) holds what is being worked on, storage keeps files when the power is off, and the power supply feeds them all.

   PracticalMedium risk

9. Technologies K–10 · Years 5–6

   Text as numbers: writing secret messages in ASCII

   Digital systems store every character as a number, so the word HELLO is stored as 72 69 76 76 79 and each of those numbers as 8 binary digits.

   Practical, model not builtLow risk

10. Technologies K–10 · Years 7–8

    Eight bits: counting to 255 and overflow

    Digital systems store integers in a fixed number of binary digits, so an 8-bit value runs from 0 to 255 and a sum that needs a ninth bit wraps around.

    Practical, model not builtLow risk

11. Technologies K–10 · Years 7–8

    Logging light levels with a micro:bit and validating the data

    Sensor data must be checked against what the sensor can report and the planned sampling times before it is queried and graphed for trends.

    PracticalLow risk

12. Technologies K–10 · Years 7–8

    Pixels, colour depth and image file size

    An uncompressed image stores an integer for every pixel, so its size is width × height × bits per pixel, plus a small header.

    Practical, model not builtLow risk

13. Technologies K–10 · Years 7–8

    Sampling sound: sample rate, bit depth and file size

    Sound is stored as a stream of integer samples, so a file's size is samples per second × bits per sample × channels × seconds, and the highest pitch it can hold is half the sample rate.

    Practical, model not builtLow risk

14. Technologies K–10 · Years 9–10

    An ultrasonic distance sensor and the speed of sound

    An ultrasonic sensor times an echo, and distance = speed of sound × time ÷ 2, so the sensor's accuracy depends on using the speed of sound for the air temperature.

    Practical, model not builtLow risk

15. Technologies K–10 · Years 9–10

    Huffman coding by hand: shorter codes for common letters

    Giving frequent symbols short codes and rare symbols long ones, with no code the start of another, stores text in fewer bits than a fixed 8 bits per character.

    Practical, model not builtLow risk

16. Technologies K–10 · Years 9–10

    Logic gates from switches: AND, OR, NOT and the two-way light

    Switches in series behave as AND, switches in parallel as OR, a push-to-break switch as NOT, and two two-way switches as the staircase light, so logical operators in algorithms have physical circuits behind them.

    Practical, model not builtLow risk

17. Technologies K–10 · Years 9–10

    One stylesheet, three pages: separating content, structure and presentation

    A web page holds its text as content, marks its structure with HTML elements and sets its look in a separate CSS stylesheet, so one stylesheet change restyles every page and the structure still serves screen readers when styles are off.

    PracticalLow risk

18. Technologies K–10 · Years 9–10

    Querying a relational database of the first 20 elements

    Data about entities and their relationships sits in linked tables, and SQL queries and joins answer questions that a single flat list handles badly.

    Practical, model not builtLow risk

19. Technologies K–10 · Years 9–10

    Reaction times from a falling ruler: validating and analysing a class data set

    A falling-ruler test turns a catch distance into a reaction time, and a class data set needs validation rules and an outlier check before its trends are trusted.

    Practical, model not builtLow risk

20. Technologies K–10 · Years 9–10

    Run-length encoding: when compression makes a file smaller and when it does not

    Run-length encoding replaces each run of identical pixels with its length, which shrinks images with long runs and can enlarge busy ones, so the benefit of a compression technique depends on the data.

    Practical, model not builtLow risk