full episodes downton abbey

Stone is hard to carve, but very easy to model, as Rob shows. This is an excellent, inexpensive and simple way to create :stone" in model landscapes and railway layouts.

Deane and Rob explore a puzzle with fractions - and find a surprising answer!

How can you cut this odd-shaped batch of toffee into two equal halves? As Rob reveals, once you think about it the right way, the answer is surprisingly simple.

There are various forms of invisible ink, but Rob shows a different way to send an invisible message.

Rob shows how the eye works to create a blind spot in everything we see, and how we get the illusion of light simply from pressure.

How does the brain decipher a picture? Rob shows the importance of masking and perspective in creating illusions of reality

Deane presents puzzles which require viewers to fold and wrap pictures in the mind.

Deane and Rob solve some more mystery letter puzzles.

This is a trick that you might want to try next time you are at a dinner with family or friends, but Rob advises that you should make sure they are sitting opposite you and not beside you - and don't bang on the table too hard if you are in a classy restaurant!

These days, most of our writing paper is A4, but it used to be foolscap. As Rob explains, it didn't get its name because some silly person made hats from it, but from its watermark. But what is a watermark?

Mucilage is the lick-and-stick glue on some stamps, envelopes and stickers. Very useful stuff and, as Rob shows, it is extremely easy to make your own, which will keep for a long time in the refrigerator once you have made it.

Deane shows how to make sound waves visible, using a cream container, a balloon
and rice grains.

Can there be such a thing as frothy rock? Rob explains how it is formed under the sea by volcanos, trapping so much steam and volcanic gas that it floats

Rob shows how to make a model boat that is powered by a simple steam jet engine.

Deane and Rob start with a length of rope which has three knots in it. When they pull the ends of the rope, the knots magically untie themselves. You'll need to try this several times before you work out why it happens!