If Mr Plant makes a mathematical mistake, then the first student to point it out gets a reward.
1) The mistake must be purely mathematical.
Errors in spelling, day of the week, order of questions, pages in a book etc do not count.
2) The mistake must have been made by Mr Plant.
In particular, the reward system does not apply if he asks a student for a numerical calculation and the student gets the answer wrong.
3) The error can be anywhere.
a) worksheets and tests (but only if written by Mr Plant),
b) on the board (but not if corrected by Mr Plant before the error is pointed out to him),
c) verbally while explaining or answering a question, and
d) on Man vs Maths.
However in all cases the student has to point out the exact place of the mistake. A claim that a sheet or test contains a mistake somewhere is not sufficient.
4) The first student to point out the mistake wins the reward, not the first person to spot it.
The first person to spot it has no more rights than anyone else.
If a student sees a mistake but tells someone else, that second person may claim the reward in full.
5) However the first person may lose their right to a reward if they:
a) shout out the answer rudely;
b) shout out the answer when someone else is waiting with their hand up;
c) are already on detention, or have been punished for poor behaviour;
d) disrupt the class by repeatedly claiming mistakes where none exist;
e) have repeatedly made a fuss about being "owed" for some previous mistake;
f) have tried to claim rewards previously to which they were not eligible.
6) Students may not opt to carry over a reward to a later time without an IOU.
Students are wasting their time asking for Mr Plant to remember a previous day's mistake. He has no memory of any previous mistakes at any time.
A student may present an IOU for a later date if a suitable reward is not immediately available. He should ask for one at the end of the class – and must be able to explain how he earned it.
7) While a student may insist on a reward for a (qualifying) mistake, they have no say on the nature of that reward.
Senior students will generally be issued with a stamp as their reward. Junior students will generally be given a lollipop or similar.
Mr Plant has whatever lollies he has, and that will not change them based on student preferences.
8) No reward will ever be earned for "being good" or any similar attempt to suck up.
Doing the day's work is expected of a lesson, and rewards will not be issued because a boy who usually does no work decides to do some for a change.
9) Attempts to get rewards for non-qualifying reasons will earn a disqualification from later rewards.