Use the following links to help you in your fact finding mission about explorers!
www.bbc.co.uk/history/historic_figures/r.shtml
http://www.kidinfo.com/american_history/explorers.html
http://mrnussbaum.com/explorersflash/
enchantedlearning.com/explorers/
Specific to Lewis & Clark
pbs.org/weta/thewest/people