Toad in the Hole
Problem
- Suppose you can buy Toad in the Hole for one person from a supermarket for £1.
Would it be cheaper to make it yourself if you want to feed a family of three?
- Shopping list:
- 400g sausages, £2
- 1 litre vegetable oil, £1.45
- 500g plain flour, 48p
- 6 eggs, £1.46
- 1 litre milk, 48p
- Ingredients required to make Toad in the Hole for three people:
- 400g sausages
- 15ml vegetable oil
- 100g plain flour
- 1 egg
- 250ml milk
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Student Solutions
You'll need to buy all the things on the shopping list - and you'll only need to buy one of each item, because each provides more than is needed in the recipe for Toad in the Hole for 3.
So...
£2 + £1.45 + 48p + £1.46 + 48p = £5.87
As the supermarket Toad in the Hole will cost £3 (3 x £1), it is cheaper to buy the ready meals!
But you would have a lot of extra oil, flour, eggs and milk left still, so maybe if you are cooking for more people (or if you want to make several meals and freeze them, or you're quite happy to have some of the ingredients left for something else) it would be cheaper to cook from scratch.
So let's see how much what we actually need for a Toad in the Hole for 3 people costs:
400g pack of sausages costs £2
If 1 litre of oil costs £1.45, then 10ml costs 1.45p and so 15ml costs 2.175p
If 500g flour costs 48p, then 100g costs 9.6p
If 6 eggs cost £1.46, then 1 egg costs 24.33p
If 1 litre milk costs 48p, then 250ml costs 12p
So the actual cost of the meal for three people is £2.46 (to the nearest penny) - rather less than £5.87, and also less than the £3 that three ready meals would cost.
Teachers' Resources
Why do this problem?
This problem is one of a series on the maths required by the Food Technology curriculum.
In this particular problem, students are required to investigate whether it is more economical to make a Toad in the Hole from scratch or to buy a ready meal.
The answer to this will depend on the number of people to be fed - and also whether you view the ingredients not required for this particular meal as waste or simply as not required immediately (so for instance, you put them away for another time or make more than you need to freeze some for later).
Problems like this give students the opportunity to practise calculations involving proportions.
Possible approach
Students could start by discussing which they think would be more economical to prepare, and what other factors might influence their decision on whether to start from scratch or not - it would be great if someone from the Food Technology department could be part of this.There are several ways in which the calculation might be approached - students could brainstorm how they might do it, and various methods be displayed so those who find it difficult to get started can choose a way that makes sense to them.
Key questions
If you know that 1 litre of vegetable oil costs £1.45, how can you calculate how much 15ml costs? (And similar questions for the other ingredients).
What is a sensible way to round calculations, where necessary?
Possible extension
What difference does it make to the conclusion if the cost of cooking is also taken into account? This will require students to find out how much it costs to heat an oven (could be gas or electric). They will also need to investigate how long the Toad in the Hole needs to cook for, and at what temperature.
Possible support
Model the sort of calculations that students will need to do before giving them the problem to work on.