As a teacher, I know how time consuming creating a lesson can be, but often others have already created the lessons you're looking for, and they are happy to share their work. Curriki is a K-12 open curricula community.  The ideas are broken out by grade level and curricular area so it's easy to search.  The site claims to have 5.6 million subscribers, and the subscription is free.  It's certainly worth checking out.