Annoying grocer
Nick Cook, School of Computing Science, Newcastle University
http://www.ncl.ac.uk/computing/outreach/resources/primary
Preamble
This activity is taken from http://www.mathmaniacs.org/lessons/fsm/ (fickle
fruite).
The purpose here is to encourage logical thinking and predicting behaviour.
It is not necessary to go into the details of Finite State Machines. The activity
could be used as the basis for pupils trying to decribe the behaviour of simple
finite state machines in real life –e.g. light switches or traffic lights.
Activity
Resources
 Instructions for the grocer
 1 hat and some bananas and apples per grocer
 A challenge sheet for customers
Workshop worksheet (ag)
Please discuss the suitability of this activity, improvements and extensions. For
example:
 Is the level appropriate to Key Stage 1 and which year?
 Are there changes you would suggest?
 Are there links to or uses in other parts of the Key Stage 1 curriculum?
 Are there links to your own practice?
Instructions for the annoying
grocer
If you are wearing a HAT:
 If the customer asks for an APPLE
Give them a banana and take off your
hat
 If the customer asks for a BANANA
Give them an apple
If you are NOT wearing a HAT:
 If the customer asks for an APPLE
Give them an apple and put on your
hat
 If the customer asks for an BANANA
Give them a banana
Instructions for customers
At each turn you can only ask for 1 banana or 1
apple.
Try asking for different fruit in turn and see
what the grocer does.
As a group, try to predict what the grocer will
do.
It is a good idea to note down what he grocer
does in response to each question.
For example:
o What do you have to ask for to get an apple
when the grocer is wearing a hat?
o What do you have to ask for to get a
banana when the grocer is not wearing a
hat?
The challenge
Ask for fruit from the grocer so that you get a
sequence of three apples in a row.