 When you think of plastic pollution, it might be images of bottles and netting washed up on a beach that comes to your mind. But have you ever heard of microplastics? Well, I've been speaking to two teenage students from Texas in the US who can explain all about it. The pair have just won a competition prize of $50,000 for creating a microplastic filtration system using ultrasound technology. Here's the moment they found out they had won.