The shape of the lesson
By the end of the lesson, learners can
- Input devices: Each input device converts something from the real world (a key press, light, sound, a pattern) into binary data the computer can process.
- Touch screens and scanners: The syllabus names three kinds of touch screen.
- Output devices: Output devices present the results of processing.
- Input: enters data for processing (keyboard, mouse, microphone, camera, scanners, touch screen).
- Output: presents or acts on results (screens, projectors, printers, speaker, actuator).
- Touch screens: resistive (pressure, two layers), capacitive (charge, finger), infra-red (beams).
- Choosing: link the device's feature to the scenario's need.
One picture every idea returns to
An input device allows data to be entered into a computer so that it can be processed; it is needed because the computer cannot process data it does not have. An output device takes the results of processing and presents them in a form people (or other devices) can use: on a screen, on paper, as sound or as movement. Input devices capture data; output devices display, produce or act on it.
Forty-five minutes, phase by phase
| Time | Phase | What happens in the room | Grouping |
|---|---|---|---|
| 0 to 5 min | Hook: predict | Open with the question in the title, Data in, results out.. A computer is useless if it cannot take in data or show what it has done. Put the figure on the board: it is the one picture every idea in the lesson returns to. | Whole class, then pairs |
| 5 to 13 min | Teach and check: Input devices | Each input device converts something from the real world (a key press, light, sound, a pattern) into binary data the computer can process. | Whole class, then pairs |
| 13 to 21 min | Teach and check: Touch screens and scanners | The syllabus names three kinds of touch screen. Your turn: A hospital wants a touch screen that nurses can use while wearing surgical gloves. Which type would you choose and why? | Pairs |
| 21 to 30 min | Teach and check: Output devices | Output devices present the results of processing. Model the worked example Choose the device on the board, one line at a time. | Corners |
| 30 to 36 min | Check | The four Stage 1 questions from the student lesson, answered on mini whiteboards or by show of fingers. Re-teach the one most get wrong. | Individual, then whole class |
| 36 to 43 min | Plenary | The exam-style questions from Stage 2, one at a time: thirty seconds alone, then a random call. The feedback lines in the key give the examiner's wording. | Individual, random call |
| 43 to 45 min | Exit and homework | Set the worksheet below (6 questions, 16 marks). Learners self-assess against the objectives before they leave. | Individual |
Protect the parts that carry the learning
The sequence carries about fifty minutes of material, so the lab is driven by one student while the class predicts rather than explored freely. Times are a guide.
Protected: the check at 30 minutes. It is the only individual read on whether the key idea landed, and it is not cut.
Cut first if the build overruns: the last check in Output devices, never the check or the plenary.
In a 60 minute block: run worksheet questions 1 to 3 in class as a Rally Coach set and model both the hardest worked example and its check live.
Corners
Put one answer or viewpoint in each corner of the room. Students move to the corner they agree with, justify the choice to a partner there, then hear one voice from each corner before the reveal.
The full structure, with its variations and the other twelve, is on the cooperative-learning page.
What to head off, and how
| Trap learners fall into | Teaching move that pre-empts it |
|---|---|
| Say why a device is an input device: it sends data into the computer for processing. | A touch screen is both an input and an output device. |
| An actuator is an output device: it receives a signal from the processor and makes something move. | Return to Output devices: ask a pair to state the correct version and show it on the lab before moving on. |
Input and output devices: worksheet
6 questions, 16 marks. Written in the style of the papers; no past paper question is reproduced.
State what is meant by an input device and an output device.
Describe how a barcode scanner reads a barcode.
Describe how a capacitive touch screen detects a touch.
A museum wants a very large interactive display that visitors can touch with a finger or a pen. Identify a suitable type of touch screen and justify your choice.
Describe how a laser printer produces a printed page.
A greenhouse system uses a motor to open a window. Identify the type of device the motor is and state whether it is input or output.
Answer key and marking notes
- Input device: allows data to be entered into a computer for processing.
- Output device: presents the results of processing (in a form the user can see, hear or use).
- Light (a laser or LED) is shone onto the barcode.
- Dark bars reflect less light and light/white spaces reflect more; sensors detect the reflected light.
- The pattern is converted into a number (binary) that the computer can process/look up.
- The screen has a layer that holds an electrostatic charge/field.
- A finger (a conductor) touching the screen changes the charge at that point.
- Sensors at the corners measure the change to calculate the position of the touch.
- Infra-red touch screen.
- It works with any object (finger or pen) and is suitable for large screens.
- A laser creates a pattern of electrical charge on a rotating drum.
- Toner (powder) is attracted to the charged areas of the drum.
- The toner is transferred from the drum onto the paper.
- The paper passes through a fuser, which uses heat to fix the toner.
- An actuator.
- It is an output device.
6 multiple-choice questions on this lesson
From the topic question bank. Assign them in the app for a marked score in your gradebook, or run the topic as a class game.
Which of these is an output device?
- Aan actuator
- Ba barcode scanner
- Ca microphone
- Da QR code scanner
A factory wants a touch screen that workers can operate while wearing thick work gloves. The screen is small and cost is important. Which type is most suitable?
- Aresistive
- Bcapacitive
- CLED
- DLCD
Which output device forms an image using millions of tiny mirrors that tilt towards or away from the screen?
- ADLP projector
- BLCD projector
- CLED screen
- Dlaser printer
A school office prints 600 letters every morning and needs them quickly. Which printer is most suitable?
- Aa laser printer, because it prints large volumes quickly and its toner lasts many pages
- Ban inkjet printer, because its ink cartridges last longer than toner
- Ca 3D printer, because it builds each page up in layers
- Dan inkjet printer, because it is faster for high volumes
A phone's capacitive touch screen does not respond when the user wears ordinary woollen gloves. Why?
- AThe glove does not conduct, so it does not change the screen's electrostatic charge
- BThe glove does not press hard enough to push two layers together
- CThe glove blocks the infra-red beams that cross the screen
- DThe glove stops the backlight from reaching the liquid crystals
Which statement correctly describes the signal conversion needed by a microphone and by a speaker?
- Amicrophone: analogue to digital (ADC); speaker: digital to analogue (DAC)
- Bmicrophone: digital to analogue (DAC); speaker: analogue to digital (ADC)
- Cmicrophone: analogue to digital (ADC); speaker: no conversion needed
- Dmicrophone: no conversion needed; speaker: digital to analogue (DAC)
Quiz key
An actuator (a motor, valve or switch) receives a signal from the processor and causes movement, so it is an output device. A barcode scanner, microphone and QR code scanner all capture data from the real world and send it into the computer, so they are input devices.
A resistive screen detects the point where pressure pushes two conductive layers together, so a gloved finger works, and it is cheap. A capacitive screen needs a conducting finger to change the electrostatic field, so ordinary gloves do not work. LED and LCD are display technologies (output), not ways of detecting a touch.
A DLP (digital light processing) projector uses a chip of tiny tilting mirrors to reflect light towards or away from the screen. An LCD projector passes light through LCD panels instead. An LED screen's pixels give out their own light, and a laser printer uses a laser to charge a drum, not mirrors to form a projected image.
Laser printers are fast and a toner cartridge prints many pages, so they suit high-volume office printing. Inkjet cartridges run out faster and inkjets are slower, so they suit low-volume home use. A 3D printer makes solid objects layer by layer and does not print letters.
A capacitive screen holds an electrostatic field; a bare finger conducts and changes the charge at the touch point, which sensors locate. Wool does not conduct, so nothing is detected. Pushing two layers together is how a resistive screen works, breaking beams is an infra-red screen, and the backlight is part of how an LCD displays, not how a touch is sensed.
A microphone's diaphragm produces an analogue electrical signal, which an ADC converts to digital data for the computer. A speaker receives digital data that a DAC turns into an analogue current to move the coil and cone. The second option has both directions reversed, and the other two leave out a conversion that is always needed between the analogue world and the digital computer.
Slides for this lesson
A projectable deck for every pack is on the way. Until then, present the student lesson full screen: its sections, figure and lab tabs follow the same order as the plan above.