"The look-arounds"
Calpurnia states that "Jem's got the look-arounds". She then follows on to say that all boys his age "have the look-arounds". This is slang for curiosity, or nosiness; she is referring to the fact that Jem is now investigating and is interested in many things. It could also be stating that Jem has got "a hunch" or uncomfortable feeling about Atticus' welfare.