KIDS Discover  Nonfiction with photo galleries and quizzes.  Includes lesson plans, infographics, spotlights, quick reads, and activities.

NASA's Climate Kids  Includes resources, videos, games, simulations, activities for weather & climate, Air, Ocean, Fresh Water, Carbon's Travels, Energy, Plants and Animals, and Technology

Discovery Education   Includes free resources and videos for teachers, parents and students and provides information on STEM initiative

TED Ed   Includes lessons and videos and much more (search by content area)
  
Science for Kids  Includes lessons and videos from all areas of Science and much more

Hands On Science Projects  Provides resources for a variety of Hands on Science projects

PBS Teachers   Provides resources by grade band and content area

Defined STEM  Provides definitions for STEM, links to resources and documents

STEM Foundations  Created by ADE, this site provides videos, lessons and classroom instructional strategies, materials and assessments that support the seven STEM foundations.

Second Grade Level Lesson Plans for Science    Provides variety of lesson plans.  You may need to explore other grade levels to find activities that match frameworks 

BrainPop Science  Variety of resources for areas of Science

ScienceBob  Variety of experiments, research, videos, and more