In this third book in the Astrid the Astronaut chapter book series, Astrid is torn between her best friend and arch-rival! The Shooting Stars and Petite Picasso groups are working together on a combined STEM and art project--which means BFFs Astrid and Hallie finally get to team up! But Astrid's excitement doesn't last long when they are grouped with her arch-nemesis: Pearl. And what's worse, Hallie actually agrees with...