The water cycle for children aged 6 to 8, hosted by Lupe, a golden retriever puppy who discovers everything alongside the child. This is the first course in the series whose axis is a CIRCLE rather than a line: the ring that opens every episode is the same four-stop loop with one stop lit, so a child always knows where they are before a word is spoken, and the arrows never stop turning even in the episodes where only one stop is lit. The Sun lifts water off the sea so quietly that nobody sees it, and about a thousand metres up — eight hundred and thirty-three children stacked head to foot — it is cold enough to become a cloud. A cloud is not cotton and it is not solid: it is billions of droplets each sitting on a speck of dust, and its bottom is flat because that flat line is exactly the height where the air turned cold enough. A droplet is far too light to fall, so it fattens by bumping into others until it has collected about a million of them, and then it drops at thirty kilometres an hour — five millimetres is the biggest a raindrop gets, because anything larger splits on the way down. Snow is not frozen rain, the commonest thing children are told wrongly: frozen rain is hail, and a snowflake is vapour that became a crystal directly, always with six points, and its journey is drawn on it. A rainbow needs Sun behind you and rain in front, it is really a whole circle, and two people standing side by side see two different ones. Lightning heats the air to thirty thousand degrees — five times hotter than the surface of the Sun — and because light arrives first, every three seconds before the thunder is one kilometre of distance. Wind is only air moving house, born where warm and cool stand side by side. And the fact the course saves for the last minute is the best one: the water in your glass is as old as the planet, and it was already rain in the time of the dinosaurs. Every stop is shown with a real photograph, and there are no exercises inside the videos and nothing to get wrong.