Scholastic and Discovery Education both offer free examples of lesson plans on their websites. A lesson plan generally includes sections for an overview of the lesson, list of objectives, materials required, each activity included in the lesson, a plan to evaluate that students understand what is taught and a conclusion.
Scholastic's website has a sample lesson plan on the topic of mythology, and the plan is geared toward new teachers, so it's very detailed. For example, it includes directions on how each lesson activity should be conducted and lists multiple assessment methods, including written projects and an oral presentation. This lesson plan is designed for a period of 4 weeks.
Discovery Education has health, arts, social studies, math, science, technology, business and literature lesson plans for kindergarten through 12th grade. Users can view lesson plans by grade range and subject level to see their components and make any adjustments if they plan to teach with the plans.
The lesson plan's overview section should include the lesson topic and explain what students will gain from learning, while the list of objectives should list all the specific skills students will learn. Learning activities should engage students and relate to real life when possible. When assessing students' understanding, it's helpful to use oral and written assignments and relate those to the plan's objectives to evaluate success.