The websites below are the ones that I use to help plan my lessons or lessons that I use in my teaching.
Education.com
Teachers Pay Teachers
PBS Learning Media
Splash Learn
Reading Rockets
Generation Genius
Mystery Science
Mr. Nussbaum
Arkansas Academic Standards
Kids Konnect
Growing Minds
Kids Health In the Classroom
EPA.gov
National Agriculture in the Classroom
Khan Academy
Edutopia
Share My Lesson
Better Lesson
Open Education Resource Commons
Scholastic Teachables
Imagine Learning EL Education
Planbook
Lesson Planet
Study.com
Teacher Vision