Describing how an automated system works

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Quick Questions

Shade in the A or B circle for each question.

1. Which answer gives the full four-part description of an automated greenhouse heater?

A The temperature sensor measures the air, the microprocessor compares the reading with the stored value, and the heater (actuator) switches on or off.

B The greenhouse gets cold so the heater turns on and warms the plants up.

2. Who compares the sensor reading with the stored value?

A The microprocessor

B The sensor

3. Which sentence shows the common mistake?

A The sensor decides to turn the fan on.

B The microprocessor decides to turn the fan on.

4. Which part of the answer is needed to explain what the microprocessor does?

A It measures the temperature of the room.

B It compares the reading with a stored value.

5. In a street light system, which is the actuator?

A The light sensor that detects darkness

B The lamp that switches on

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1The temperature sensor measures the room temperature.		AThe sensor keeps measuring and the process repeats.
2The microprocessor compares the reading with the stored value.		BThe microprocessor switches on the actuator, a heater, if the reading is below the stored value.
3The actuator is the part that responds when the microprocessor decides action is needed.		CStep 1 of the answer: name the sensor and say what it measures.
4A complete answer says the process repeats continuously so the system keeps checking.		DThe answer misses the sensor, the stored value and the actuator, and it does not say the process repeats.
5The sensor decides to turn on the heater.		ESensors only measure and send data. The microprocessor makes the decision by comparing the reading with the stored value.
6The microprocessor checks the temperature and the heater turns on.		FStep 2 of the answer: the microprocessor makes the decision by comparing the reading with a stored value.

Definitions

sensor, microprocessor, stored value, actuator

Fill in the Blanks

Complete each line of code by filling in the missing parts.

The ______ measures the temperature.

The sensor only measures. The ______________ makes the decision.

The microprocessor compares the reading with the ____________ in its memory.

If it is too hot, the microprocessor tells the ________ to switch the fan on.

The process _______ so the sensor keeps measuring and the system keeps checking.

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A Sensor measures temperature

B Sensor compares it

C with the stored value

D Actuator turns the heater on

E The process repeats

Question 2

A Sensor measures brightness

B Actuator compares it

C with the stored value

D Actuator switches the lamp on

Question 3

A Sensor measures soil moisture

B Microprocessor opens the valve

C with the stored value

D Actuator opens the valve

Question 4

A Actuator measures air pressure

B Microprocessor compares it

C with the stored value

D Actuator opens the vent

Question 5

A Microprocessor measures speed

B Microprocessor compares it

C with the stored value

D Actuator applies the brakes

E The process repeats

Answer Key

Describing how an automated system works

Section A: Quick Questions

A — The temperature sensor measures the air, the microprocessor compares the reading with the stored value, and the heater (actuator) switches on or off.

A — The microprocessor

A — The sensor decides to turn the fan on.

B — It compares the reading with a stored value.

B — The lamp that switches on

Section B: Match the Pairs

The temperature sensor measures the room temperature. → Step 1 of the answer: name the sensor and say what it measures.

The microprocessor compares the reading with the stored value. → Step 2 of the answer: the microprocessor makes the decision by comparing the reading with a stored value.

The actuator is the part that responds when the microprocessor decides action is needed. → The microprocessor switches on the actuator, a heater, if the reading is below the stored value.

A complete answer says the process repeats continuously so the system keeps checking. → The sensor keeps measuring and the process repeats.

The sensor decides to turn on the heater. → Sensors only measure and send data. The microprocessor makes the decision by comparing the reading with the stored value.

The microprocessor checks the temperature and the heater turns on. → The answer misses the sensor, the stored value and the actuator, and it does not say the process repeats.

Section C: Definitions

sensor, microprocessor, stored value, actuator — Describe the system: the sensor measures, the microprocessor compares the reading with a stored value, the actuator responds, and the process repeats.

Section D: Fill in the Blanks

The sensor measures the temperature.

The sensor only measures. The
microprocessor makes the decision.

The microprocessor compares the reading
with the stored value in its memory.

If it is too hot, the microprocessor tells
the actuator to switch the fan on.

The process repeats so the sensor keeps
measuring and the system keeps checking.

Section E: Spot the Error

B — The sensor only measures. The microprocessor does the comparing, so line 2 should be 'Microprocessor compares it'.

B — The actuator only responds, for example by switching on the lamp. The microprocessor compares the reading, so line 2 should be 'Microprocessor compares it'.

B — The microprocessor compares and decides, but it is the actuator that opens the valve. Line 2 should be 'Microprocessor compares it'.

A — Measuring is the job of the sensor, not the actuator. Line 1 should be 'Sensor measures air pressure'.

A — The microprocessor does not measure anything. The sensor measures the speed and sends the reading on, so line 1 should be 'Sensor measures speed'.