Martha is mortified when she gets a lowly A minus for her latest history assignment, the equivalent of a fail for Martha. She decides to frantically swot, but is so exhausted her grades threaten to slip even further.
The girls have been campaigning hard for a new school library. When Mrs Griggs announces that the library campaign has been successful, joy turns to horror when the girls learn their favourite tree will need to be cut down.
The girls have teamed up to enter a national young inventors competition. Lily and Martha fall out when Lily leaves the team to join Matt's team, and Martha replaces Lily with super-geek Roxanne Bunce.