Helps learners and educators improve elementary learning worldwide by making personal education tools available. Learn more than 5,000 math and science topics at a speed that suits you. Math topics include arithmetic, measurement, algebra, geometry, probability, statistics, trigonometry, analysis, and calculus. Science subjects include geography, life science, physical science, biology, chemistry, and physics. Other subjects include SAT exam prep, engineering, technology, astronomy, English, and history.

Website: http://www.ck12.org/

What Users Love About the App

“I LOVE this site. It has wonderful applications for students with different learning styles. I love the adaptive practice and the feedback it offers. I collect data and I can see where the student is in understanding that concept.”

“A very good resource for remote learning. Topics are well-organized and lessons are short, which makes them easier to digest for students. It also does all the grading! Right now, it is mostly for STEM courses. I could not be more satisfied.”

“The site maintains a solid balance between structure and creativity. Students are able to control their own learning and access helpful resources. It allows teachers to switch roles from directing the learning to guiding the learning.”

“This is a fantastic resource for teachers who struggle to find textbooks that are specific to their curriculum. Very user-friendly and the staff are really helpful. I love the adaptive quizzes because my students who are struggling don’t get frustrated, and my high fliers can be challenged with no extra effort from me. Thank you, CK-12.”

“I have used the site for at least 6 years and have never once received a cease and desist order for using this site. I have used CK-12 ever since. I recently noticed that they have greatly upgraded their website and I am eager to learn more.”

“Excellent STEM education resources and online community of teachers, students, and study groups. One FlexBook that is very impressive is High School Introduction to Engineering; it is awesome. It guides students through Real Engineering “Best Practices” with Design Projects, and more.”

What Users Dislike About the App

“The interactives often lack rigor, and most primary students would find CK-12 too complicated to access on their own.”

“I wish this app was advertised more. I learned that it has been around for 6 years, but this is the first I’ve heard about it.”