This title is part of Bug Club, the first whole-school reading programme that joins books with an online reading world to teach today's children to read.
In this Yellow-B level Zip and Zap book: Zip and Zap travel to Earth, and meet two children, Liz and Sam.
They play happily in the snow together all day. Zip and Zap take a snowman home with them, thinking it's Sam.
When it melts, they think it's because Sam didn't like them - but then they see Liz and Sam waving to them from Earth!