In order to discover what rainbows are made of Penelope K sets about trying to make one.

'Tears' - Penelope K goes to enormous efforts to cry in order to answer a question about what tears are made of, but nothing seems to work. 'Worm' - Penelope Ks investigations as to whether worms have eyes lead her on an underground journey with very surprising results.

'Biggest Animal' - Penelope K is baffled by some facts which lead her to suspect that the biggest animal in the world could be a giant chicken-fish. 'Head' - Seeing the back of her own head proves more challenging than Penelope K suspected.

'Night' - A spinning earth mobile, a desk lamp and a phone call from some travelling fish help Penelope K understand that its night on the side of the world that is facing away from the sun. 'Boomerang' - Penelope K decides not to throw a boomerang in case she loses it. But the child who owns it discovers that if you throw it it comes back to you!

'Emu' - Investigating why emus need feathers leads Penelope K on a voyage of discovery involving fishs fins, dogs tails, peoples hair, animals fur and a nice, warm feather quilt. 'Snails' - Penelope K investigates the slippery issue of snails shells where exactly do they get them from?

'Elephant' - Penelope K puzzles over the many uses of an elephants trunk. 'Dog Sniff' - When shes asked why dogs sniff so much, Penelope K explores a world of wonderful smells perfume, flowers, carrots and campfires.