According to Murphy's Law, "If things can go wrong, they will go wrong". For instance, if the toast we made for breakfast slides off our plate, Murphy's Law says it will usually land butter-side down. Many people think that's exactly what happens - but are they right, and why?

This worksheet describes a series of experiments to find out the truth behind Murphy's Law of Toast. You will need:

1. A slice of lightly-toasted bread (toasted well enough to turn the bread rigid, but not burnt and fragile)
2. Some butter.
3. A plate without too high a rim (to ensure the toast slides off smoothly - a paper plate would be fine)
4. A thick marker pen
5. Some newspaper to spread on the ground

There are three experiments. The first is designed simply to find out if it really is true that if our toast slides off a plate and on to the floor, it usually lands butter-side down. The second experiment then investigates the most common explanation for toast landing butter-side down: that it's due to the presence of the butter. Finally, the third experiment investigates one way of curing Murphy's Law of Toast.

Experiment 1: Does toast usually land butter-side down ?

1. Find yourself a clear area of uncarpeted floor, and spread out some newspaper.
2. Take your slice of toast and spread some butter on one side of it - just the usual amount you'd put on for a snack.
3. Place the toast, butter-side up, on the plate and hold the plate at around waist-height (as you would when, say, walking to the breakfast-table).
4. Now, standing over where you've spread the newspaper, steadily tilt the plate downward until the toast slides off and tumbles to the ground
5. Make a note of whether it landed butter-side up, or butter-side down.

Carry out a series of 20 drops - this will help reduce the effect on one-off flukes and lucky bounces on the final result.

Experiment 2: Is the butter to blame ?

Many people think that it's the butter that's to blame for the butter-down landings. If that's true, then unbuttered toast should slide off the plate but land facing the same way up as it started. If it does the same as buttered toast and turns face-down, however, the cause of the face-down landings must lie in the toast itself.

To find out, repeat experiment 1 with a fresh piece of unbuttered toast. But this time, instead of butter, just put a letter "B" on one side with the marker pen. Then go through steps 3 to 5, starting with the "B" side uppermost on the toast, and see how many times the toast slides off the plate and lands with the "B" side facing down (the equivalent of butter-down landings).

1. Again, carry this out 20 times, and record your findings.

When toast slides off a plate, it topples over the edge and begins to spin. It's been suggested that if only we humans were taller, we'd hold our plates higher off the ground - and thus give the tumbling toast more chance of completing a full 360-degree turn. Calculations suggest that toast tumbling from a height of at least 2.5 metres stands a better chance of landing butter-side uppermost.

But would taller humans really stand a better chance of beating Murphy's Law of Toast ? To find out, repeat Experiment 1 with the buttered toast again - this time letting the toast slide off the plate from a height of 2.5 metres. Repeat 20 times, and record your findings.

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