Unit studies are a popular homeschooling method because they can be hands-on, literature-based, or even geared towards the Charlotte Mason method. Unit Studies typically eoncompass all of the scholastic subjects through the study of one topic (Weaver units or KONOS character units, for example), although they can be specific to a specific subject (Evan-Moor science units or Teacher Created Materials units, for example). For more information on unit studies, be sure to read Robin Sampson's article Unit Study Approach. Grace E., a homeschooling mom using Weaver unit studies has written and excellent article on her approach.
Five In a Row
TheHomeSchoolMom's Free FIAR Resources
Weaver Curriculum:
KONOS
TheHomeSchoolMom's Free KONOS Resources
Thematic Units by Teacher Created Materials
Evan Moor Units:
TheHomeSchoolMom's list of Free Unit Studies Online