CK-12 Interactive Math Series

CK-12 Interactive  Math Series

CK-12 Interactive Math is a series of free, online courses closely aligned with the Common Core State Standards for Mathematics (CCSS). CK-12 offers many other free courses as well, but I’m limiting this review to the math courses for middle school and high school because they share common features. Courses covered in this review are:

Middle School Math 6 for CCSS
Middle School Math 7 for CCSS
Middle School Math 8 for CCSS
Algebra 1 for CCSS
Geometry for CCSS
Algebra 2 for CCSS

These courses include the features of a typical textbook along with enhancements made possible by the online presentation. They are presented in a number of units, and each unit has many subsections that I will call chapters.

Each chapter works through a progression of explaining new concepts, demonstrating applications, providing example problems, and giving students problems to solve on their own (not necessarily in that order). These courses sometimes include videos within lessons that provide additional instruction. Most lessons include interactive exercises and simulations. (Many more are available for free on the website under "Explore" then under PLIX.) Socratic-type questions were purposely built into these courses to introduce new ideas and to help students think more deeply about math concepts. Some lessons include a question labeled "Discussion Question" for which an actual, real-time discussion is best, but students can provide written answers instead if need be.

A "Student Tutor" feature provides additional help that should be available for math courses by May of 2022. This is a chat-style assistance that students access by clicking on the Gumby-like character to open the chat bar and submit questions. There are preset answers to common questions, but the CK-12 team will try to answer others.

Many of the interactive activities ask students to answer just one question at a time as they are learning a new concept. Students are given immediate feedback and the opportunity to try again until they get it right. Explanations are included with both correct and incorrect answers. This ensures that students understand the concepts as they are being taught rather than waiting until they are attempting to solve a series of problems at the end of the chapter.

The interactive simulations have students use built-in tools to manipulate items on the screen, all without having to download other programs. (Some other publishers' online math courses require students to use external programs or go to other websites for simulations.) Everything is built right into the lessons. However, students are directed to use a calculator from time to time in these courses.

Practical applications and word problems are used frequently throughout these courses to help students understand concepts and how math is used in real life. Here’s just one example of how this works. The first chapter in Middle School Math 8 for CCSS is on congruence. Congruence is introduced through an explanation of techniques used to create motion in video games. Students learn about translations, reflections, and rotations as they explore each of these with interactive exercises and questions. Grasping the concepts of translations, reflections, and rotations as they are used to create video games makes it easier for students to understand the explanation in the last half of this unit about how a coordinate plane can be used to create translations, reflections, and rotations.

In all of the courses, each lesson concludes with a set of online practice questions that are immediately scored by the program. These are supposed to be adaptive, changing the problems presented to the student based on how well they handle previous problems, although I have no way to judge to what extent that happens.

The courses are tightly aligned with the Common Core State Standards for Mathematics which introduce algebra and geometry well before high school and teach statistics and probability at all levels. Consequently, the middle school courses have a great deal of algebra and geometry. By the time students reach Algebra 2, they will be learning topics often found in precalculus and calculus courses.

Even though some of the content is advanced, the courses teach each concept through different learning modes (e.g., textbook explanation, video instruction, simulation, practical application), making it easier for students to learn. While these courses were not designed exclusively for independent study, students should be able to work through most of the lessons on their own.

Parents need to set up teacher accounts, create classes, enter students, and make assignments. Students need separate accounts. (Both students and teacher accounts are free.) Students complete most of their work online, and the program tracks their progress. The Student Insights feature in the teacher's account alerts you to potential issues a student might be having.

All courses have a free companion “teacher edition” that you can find under “Other Versions” on each course’s opening page. The teacher editions differ greatly for the various grade levels. Those for the courses for grades 6, 7, and 8, as well as Algebra 2, have the complete student text as it appears online to the student, a few teaching notes, and answers to the few problems that appear within chapters, such as the discussion questions. Other courses have instructional information, lesson plans (sometimes called pacing guides), and links to files with solutions, but they don’t have the actual student text within the teacher edition. For the courses with separate files with solutions, I found it a little cumbersome getting to the separate file for each chapter, so I would suggest that you print them out and keep them in a binder.

The Algebra 1 and Geometry courses have quizzes and exams that are found in the teacher edition material. The courses for grades 6, 7, 8, and Algebra 2 have zipped files of chapter assessments that are available upon request. (This is not mentioned on the website, so you will have to ask!) You can also create your own quizzes or tests for any of the courses using a built-in tool on the CK-12 website. Click on the Library tab, then click on “Create New” and it will walk you through the process. This is a sophisticated feature that should be helpful if you want to tailor your tests or create one that isn’t included for a course.

Following are the titles for the units within each course and a few notes particular to Geometry and Algebra 2.

Middle School Math 6 for CCSS

Titles for the ten units in this course are Ratios, Rates and Percentages, Division with Fractions, Operations with Decimals and Whole Numbers, Rational Numbers, Expressions, Equations, Inequalities, Surface Area and Volume, and Statistics.

Middle School Math 7 for CCSS

Titles for the eight units in this course are Ratios and Proportional Relationships; Operations with Rational Numbers; Expressions, Equations, and Inequalities; Percents and Proportional Relationships; Investigating Angles and Shapes; Area and Volume of 2-D and 3-D Figures; Probability; and Population Statistics.

Middle School Math 8 for CCSS

This course is presented in ten units titled Congruence, Similarity, Linear Equations, Linear Relationships, Systems of Equations, Patterns and Associations in Data, Functions, Volume, Integer Exponents and Scientific Notation, and Irrational Numbers and the Pythagorean Theorem.

Algebra 1 for CCSS

Algebra 1 has five units titled Introduction to Functions; Expressions; Functions; Equations and Inequalities; and Data, Statistics, and Probability.

Geometry for CCSS

The 11 units in the Geometry course are titled Basics of Geometry, Rigid Transformations, Congruence, Reasoning and Proof, Constructions, Similarity, Trigonometry, Circles, Three Dimensions, Conics and Coordinate Geometry, and Applications of Probability.

The Geometry course uses videos and interactive exercises as in the other courses. While the Geometry course uses interactive activities like the other courses, the unit on constructions also teaches students traditional methods for creating geometric constructions using a pencil, a compass, and a straightedge. However, they rarely use paper and pencil for constructions in the rest of the course. Geometry students also learn to write proofs in various formats: paragraph, two-column, and flow diagram.

Instructions for a project are found in the teacher material. The project—to draw up detailed, architectural plans for a living space—is intended to be completed by students working cooperatively as teams, so you might want to adapt it if you have a single student.

Algebra 2

The units in Algebra 2 are titled Polynomials, Functions, Quadratic Functions, Polynomial Functions, Exponents and Logarithmic Functions, and Rational Functions. Three additional units are still under development: Trigonometric Functions, Working with Data, and Sampling. (The course will be sufficient even without the forthcoming units.) It has the same type of teacher edition as do the courses for grades 6, 7, and 8.


These free CK-12 Interactive Math courses offer outstanding course material that utilizes technology in a way that is totally accessible for homeschooling students.

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Instant Key

  • Need For Parent or Teacher Instruction: minimal
  • Learning Environment: independent study plus discussion
  • Grade Level: grades 6-12
  • Special Audience: gifted
  • Educational Methods: traditional activity pages or exercises, multisensory, life applications, interactive, discussion, critical thinking
  • Technology: video, supplemental digital content, online, adaptive
  • Educational Approaches: traditional, eclectic
  • Religious Perspective: secular

Publisher's Info

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