Nina investigates why Grandpa Jim's face is wrinkly with the help of Luke, her sight neuron.

Experimenters Chloe and Jodi bring their grandpa to Nina's lab and discover that his face wasn't always wrinkly. When he was younger his skin was smooth like theirs. They do an experiment with some stretchy material and find out that skin is elastic. This means that when it is stretched, it pings back to how it was before. But Grandpa Jim's skin doesn't ping back as quickly as the girls' does.

Then they all go to a beauty salon and Nina and the twins have some face masks put onto their skin. They try to pull faces for Grandpa Jim but the hard masks stop them from moving their faces. Nina explains that people need their skin to be stretchy and elastic so that they can make faces, talk and move their bodies.

Back in the lab, they discover that when people move their faces to smile, talk or frown, their skin stretches and crinkles up in certain places. When people get older, the skin doesn't smooth back out again because the body makes less of something called collagen. So they get wrinkles in the places that were crinkled up. This is a natural part of growing older. Show less