This free online educational application, Reading Comprehension Books 1, is appropriate for all ages and skill levels. It helps expanding your background knowledge as well as vocabulary explicitly while having fun. Moreover, this free application is specially designed for both native speakers as well as students learning English as a second or third (or more) language.
Kids, teenager and even adults love practicing these reading comprehension worksheets which can be one of a good educational online test. This is simply because it teaches you about grammar, sight word vocabulary etc.