I would suggest this book. It's about 250 pages, but a broken down digestible read and you can relate the stories within to your 8 year old. It's only about $15 in paperback. https://www.amazon.com/Golden-Age-Piracy-Behind-Pirate/dp/1510738754/ref=asc_df_1510738754/?tag=hyprod-20&linkCode=df0&hvadid=552882832481&hvpos=&hvnetw=g&hvrand=5278765483288104314&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=1018511&hvtargid=pla-976949717642&psc=1