Clara acknowledges that Danny brings out the best in the kids. They look up to him and trust him as their teacher. They desire his praise and strive to impress him. Clara treats the Doctor in the same way but does he bring out the best in his companions? The Doctor may be a catalyst for change but he has no control over what the people he inspires do with the opportunities they are given. Ruby represents the tipping point between rigidity (lack of imagination) and creative thinking. She is a literal thinker. And yet when exposed to new things, for example the cross-section of the tree in the museum, she is able to intelligently question and wonder. This is a time in her life where it could go either way depending on the guidance she is given. Similarly, Clara is deciding whether to follow a traditional path or make her own way.