Sam, a 7-year-old tortoise, loves to hear his Grandad Charlie tell stories about different animals or plants - and why they are the way they are. The stories that Grandad Charlie tells have been passed down to him through generations of tortoises; they started out when a small tortoise overheard them many many years ago. Each story told has one or two key ideas based on Darwin’s theory and relevant to the science curriculum for 6 to 10 year-olds. For example: animals evolve over time and different animals have different useful features such as trunks or shells. At the end of each story Sam asks Grandad Charlie a question about what he has heard.