A nice easy question to start the term with:

You go to the supermarket to buy your favourite shower gel (or other product). It usually costs £2.99. You have three £1 coins ready, when you notice the price has temporarily been reduced to £1.

What is the most money you can save?

Hint: Think of future gain

Solution:
It’s not the obvious £1.99 saved – that is instant gratification.

It is actually better to buy 3 bottles:

Saving = Actual price x 3 – Reduced price x 3

Saving = £2.99 x 3 – £1 x 3 = £8.97 – £3 = £5.97

If you spent the whole £3 (which is one bottle plus one pence), you get a long term saving which is worth far more, for just 1p more.

Teaching the concept of delayed benefit is rather useful, especially if you are trying to encourage open investigations or looking at time spent on personal revision.