Chuck's courage is revealed when Miss Caroline is suddenly scared witless by some unknown creature.
'It's alive she screamed,' Chuck then proceeds to gather a crowd together to find this unknown creature. Not only does this show his courage but also his leadership skills.
This courage makes Chuck seem mature for his age due to the fact that most children his age wouldn't dare muster enough courage to chase after some unknown animal, which could very well be a mouse.
This maturity is in part to thank for the fact that he's got a group of people to help him find the animal. Due to the fact that they see him as someone to look up to and follow.
Furthermore, this courage leads Scout to respect him despite the fact that he's in the same financial deposition as Walter Cunningham
'Chuck Little didn't know where his next meal was coming from, but he was a born gentleman.'
Reinforcing the main theme of this book which is prejudice.