Building Sandcastles

Go and Stop are having fun playing at the beach. They see their friends the Three Bears building sandcastles. Little Bear's sandcastle looks very impressive, especially when Go puts a shiny shell on top. Medium Bear starts to make his, but when he tips his bigger bucket over, he just makes a sandy mess. Stop and Go realise that differently sized buckets need different amounts of sand. Big Bear's bucket is even bigger! Will they figure out how to fill her bucket and build another sandcastle?