A fitness tracker is worn on the wrist and uses an embedded system to count the wearer's steps.
Explain one reason why an embedded system is used in a fitness tracker.
Mark scheme
Award up to two marks for a linked explanation such as:
- The battery lasts longer/needs charging less often (1) because embedded systems have low power consumption/use less power (1)
- It can be made small/light enough to wear on the wrist (1) because the processor, memory and input/output are combined on a single chip/microcontroller (1)
- It can carry out the step-counting function reliably (1) because it runs a single/dedicated program and cannot install other software (1)
- It has a low cost per unit (1) because it uses fewer/less powerful components than a general purpose computer (1)
For both marks, the expansion must follow/associate with the statement.
Award one mark for a valid point stated on its own, e.g. 'it is small/light enough to wear on the wrist' (1) or 'its battery lasts longer before it needs charging' (1).
Accept the same linked ideas in either order, e.g. 'it uses less power (1) so the battery lasts longer (1)'.
Do not accept 'it uses less power'/'low power' on its own as a complete explanation; it must be linked to the battery lasting longer/needing charging less often for the second mark.
Do not accept an expansion that simply restates the point, e.g. 'it is small (1) so it fits on the wrist' earns only the point mark; 'fits on the wrist' is not a linked cause and is not enough for the second mark.
Do not accept 'the battery is small' as the linked reason for low power consumption.
Do not accept responses that say other software/apps can be installed on an embedded system (0); embedded systems have a single/dedicated function and cannot install new software.
Example answers and how they were marked
The battery lasts longer before it needs charging because an embedded system has low power consumption.
Why: Point (1) and linked reason (1); low power consumption explains why the battery lasts longer.
It is small so it fits on the wearer's wrist.
Why: Point 'small' earns (1); 'fits on the wrist' restates the point rather than giving the linked cause (components combined on a single chip), so no second mark.
It can run other apps as well because it is a tiny computer.
Why: Misconception that embedded systems can install other software; no creditworthy point or linked reason.