Website review by
Polly Conway, Common Sense Media
CK-12 Website Poster Image
Quality, well-organized math and science lessons.

Parents say

age 9+
Based on 4 reviews

Kids say

age 15+
Based on 9 reviews

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The parents' guide to what's in this website.

Educational Value

Kids can learn STEM subjects ranging from subtraction to nuclear physics, plus extras like economics and SAT prep. They'll learn study skills and can track how well they're doing by looking at their quiz results over time. Some subjects, like anatomy, require straightforward memorization, while others, like life science, will encourage kids to reflect on their world and how its pieces fit together. 

Positive Messages

CK-12 makes STEM content accessible to kids with all learning styles and could be the key to mastery for some. 

Drinking, Drugs & Smoking

What parents need to know

Parents need to know that CK-12 is a website that offers a variety of free lessons in STEM subjects (Science, Technology, Engineering, and Math). The site breaks down traditional book chapters into smaller, bite-size ideas that may be easier for kids to digest. Although it's called CK-12, most of the available content is probably best suited to older kids and teens; many advanced subjects are covered. Information for younger kids also is on the site, but you may have to help them find it. Under the CCPA law you have the right to protect your personal information. Make a Do Not Sell request to CK-12.

User Reviews

  • Parents say
  • Kids say
Adult Written byJessica D January 8, 2018

Easy to use

I’m brushing up on my math skills in preparation for some college classes.
Parent of a 14 and 15-year-old Written byRamandi December 14, 2015

CK-12 - Digital curriculum at its best is a great resource for everything from full textbook-like curriculum (called FlexBooks) to individual multi-modal learning resources such as videos,... Continue reading
Teen, 15 years old Written byqwertyuiop09876... April 29, 2019

Don't use it. Very Glitchy. Questions dont make sense

It does not provide enough information to answer the questions, and their reading sections are 90% useless information that will not be one of the questions. Th... Continue reading
Teen, 16 years old Written byCaleb_M September 19, 2016

Problems with Problems

Ck-12 has a very nice layout but the total program is horrible. It offers no help in answering questions that you might have on a problem and is useless besides... Continue reading

What's it about?

CK-12 is divided into three sections: Mathematics, Science, and More. Mathematics includes subjects from arithmetic to trigonometry and statistics. Science covers all the bases: biology, chemistry, and physics, as well as life, earth, and physical sciences. The More section offers history, technology, and economics. Within each subject, you can click on a circle to get even more specific; each contains a number of Concepts, which are short, chapter-like lessons. For example, if you click on \"phases of matter\" within the physical science section, you will be given a list of topics that include evaporation, sublimation, and solutions. Within those, you can choose from a series of modalities: read, study aids, video, or web links.

You can bookmark material you'd like to save for later, or you can send it to a classmate by email or social media. Kids can create groups to share content with each other. If you're looking for a very specific topic, enter it into the search box to go straight there.

Is it any good?

Material on the site is well organized and very accessible. CK-12 likely will appeal most to kids who are already fairly studious; it doesn't oversimplify ideas. Although it does cover simpler subjects like arithmetic, its presentation might be too advanced for kids of the appropriate age to understand on their own. It's perfect with a parent's help, however.

CK-12 is very committed to reaching kids with all types of learning styles, and the inclusion of video, audio, quizzes, and other tools may open doors for kids who are having trouble in the classroom. The site is essentially transforming a textbook into a multimedia experience, which is very exciting. There's another major bonus: all this content is free! And it's available in nearly 50 languages. Some subjects contain more content than others, but teachers are adding lessons all the time, and the site should continue to grow.

Talk to your kids about ...

  • You can talk with your kids about why it's important that both boys and girls learn about math and science. Explain that people haven't always believed this. 

  • Many animated movies popular with kids feature detailed ecosystems, like A Bug's Life and Ice Age. When your kids watch these movies, point out those worlds and ask them to describe them. 

Website details

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