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Grade 8: CK-12 Middle School Math Concepts Grade 8


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This resource was reviewed by OSPI in Spring 2015. Learn more about the review process and the data analysis approach.

The version reviewed was last updated: 2/26/2015.

Background from OER Project Review Team
CK-12 Foundation is a non-profit organization that creates and aggregates curated STEM content. Editing tools are built into the online system to facilitate personalization of content. Multiple formats allow for creation of device agnostic materials. The CK-12 platform offers many supplemental video, audio, and interactive, learning objects and real-world applications that can be accessed to adapt and remix the Flexbook. This should factor into the viewer

IMET (Learn more)

Chart with scale from 0 (Strongly Disagree) to 3 (Strongly Agree). Consistent Content: , Rigor & Balance: , Practice Connections: , Standards for Math Content: , Quality Indicators: .

EQuIP (Learn more)

Revision needed (3.0)
Chart with scale of 'meets criteria' from 0 (None) to 3 (All). Alignment: 0.5, Key Area of Focus: 1.25, Instructional Supports: 0.75, Assessment: 0.5.
Chapter 9: Linear Functions and Graphs

Achieve OER (Learn more)

Chart with scale from 0 (Weak) to 3 (Superior). Explanation: 1.75, Interactivity: 2.0, Exercises: 1.25, Deeper Learning: 0.75.
Chapter 9: Linear Functions and Graphs

See standard error chart for the review scoring

Reviewer Comments (Learn more)

Moderate (3.0)

Comments/Ideal Use:

The structure of the lessons is easy to follow. All lessons begin with a problem, presentation of concepts, guided practice, more practice, and supplemental video. There are additional resources available on the CK12 website (but they are not linked to the lessons or standards, which makes them hard to find).

This material could be used by a teacher who is trying to quickly get students through middle school content that is heavy on procedure. This is best used by students in an independent online setting.


  • More than half of the lessons address non-grade 8 materials - lessons on percent, probability, integers, and polynomials
  • Many 8th grade standards are not addressed in the materials - 8.SP.4, 8.EE.3 and 8.EE.4 have no associated lessons
  • Lessons do not focus on conceptual understanding
  • There are no teacher support materials, no assessments, and no mention of the Standard for Mathematical Practice


  • These materials appear to have been compiled from existing lessons that were developed outside of CCSS. The developer should consider creating new lessons that address the full intent of the CCSS where they do not have lessons that do so.
  • Eliminate lessons that are not on grade level, and develop more rich lessons that do address grade level 8 standards.
  • Design lessons that allow students to develop deeper conceptual understanding.

Comments/Ideal Use:

The curriculum does a good job of introducing relevant vocabulary/terms. Good use of Khan Academy videos to support lessons.

It would require some serious work to use this resource. The teacher would have be fairly experienced to use this curriculum effectively in the classroom.


  • No teacher/pacing guides or assessments present. No rubrics or answers for student materials were present.
  • The CCSS-M standards and practice standards were not explicitly listed or linked to lessons/units.
  • The complexity and variety of problems was low. Rich tasks and problems that engage students in "productive struggle" need to be present.
  • Small group/cooperative learning activities were not present. Students were not asked to conjecture about math ideas or encouraged to create models of their understanding.


  • Major revision to curriculum to encourage more use of models, exploration, and use of discourse.

Comments/Ideal Use:

The online practice problems are adaptive and extensive. The content is solid for the areas that are covered - Strong, accurate explanations of mathematical concepts.

The resource, as it currently exists, should be used by experienced teachers to assign practice problems that supplement problems that emphasize conceptual understanding and critical thinking.


  • Lack of summative assessments
  • Lack of pacing guide, teacher's guidance
  • Some 8th grade Common Core Math standards are not covered or not covered fully. Content areas that are missing or need improvement:
    • approximating irrational numbers (incomplete)
    • negative exponents
    • evaluating cube roots of small perfect cubes
    • compare two different proportional relationships
    • use of similar triangles to explain why the slope is the same between any 2 points on a line
    • Does not address solving equations that have no solution or many solutions
    • Comparing properties of functions each represented in a different way
    • graph a function given a verbal description
    • congruence in context of transformation
    • similarities in context of dilations
    • describe sequence of transformation given two similar figures
    • explain a proof of the Pythagorean Theorem
    • two-way tables
  • Mathematical Practices are not incorporated - constructing viable arguments; critiquing others' arguments, etc.


  • Include summative assessments for lesson that meet 8th grade Common Core standards
  • Create teacher's edition that includes a pacing guide
  • Incorporate these contents areas in above list
  • Expand exercises to include problems in which students need to construct viable arguments, critique others' arguments, think critically, etc.

Comments/Ideal Use:

The idea that teachers can create their own versions of the flexbook by adding modules and removing modules is a good part of this curriculum. I tested the flexbook part of CK-12, and was pleasantly pleased with how well it worked. The situations presented in the problems and exercises are very pertinent to the real world. In chapter nine there are many situations presented from football games to hiking to movies, which will make math relevant to the students.

If the adaptations were made, this would be an excellent curriculum for a school to follow.


  • There is no curriculum map or pacing guide for this curriculum.
  • Many of the chapters focus on standards from previous grades. Chapter 7 is the first chapter that is dealing with standards from the grade level.


  • Create some sort of pacing guide, similar to the one available for 6th grade.
  • Maybe the 1200 page textbook should be divided into two different textbooks. One that focuses on review and one that adheres more closely to the standards.

Creative Commons License
This work by the Office of Superintendent of Public Instruction is licensed under a Creative Commons Attribution 4.0 International License.