CK-12,org Top Content for 2014

2014 was (another) active year of learning for CK-12 users. Presenting this year's most used content by students and teachers on CK-12. We look forward to 2015!
Top 5 FlexBooks
Earth Science for Middle School
Physical Science for Middle School
Life Science for Middle School
Chemistry Second Edition

Top 10
Science Concepts

1Characteristics of Life
2Prokaryotic and Eukaryotic Cells
3Cell Biology
4Scientific Method
5Rocks and Processes of the Rock Cycle
6Organization of the Human Body
7Food Chains and Food Webs
9Scientific Explanations and Interpretations
10Asexual vs. Sexual Reproduction

Top 10
Maths Concepts

1Faces, Edges, and Vertices of Solids
2Two-Column Proofs
3Basic Geometric Definitions
4Addition of Integers
5Surface Area of Triangular Prisms
6Order of Operations
7Same Side Interior Angles
8Triangle Sum Theorem
9Area and Perimeter of Triangles
10Rectangular to Polar Form for Equations