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CK-12 Geometry Concepts

CK-12 Foundation/Kathryn Dirga, Lori Jordan

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Note that this resource was reviewed during the Spring 2014 review period. The resource may or may not have been updated since the review. Check with the content creator to see if there is a more recent version available.


This resource was reviewed by OSPI in Spring 2014. Learn more about the review process and the data analysis approach.

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’s analysis of the review results.

IMET (Learn more)

Chart with scale from 0 (Strongly Disagree) to 3 (Strongly Agree). Consistent Content: 2, Rigor & Balance: 2, Practice Connections: 1, Standards for Math Content: 1, Quality Indicators: 2.

EQuIP (Learn more)

Revision needed (6.2)
Chart with scale of 'meets criteria' from 0 (None) to 3 (All). Alignment: 1.4, Key Area of Focus: 1.8, Instructional Supports: 1.8, Assessment: 1.2.
Chapter 12: Rigid Transformations

Achieve OER (Learn more)

Chart with scale from 0 (Weak) to 3 (Superior). Explanation: 2.2, Interactivity: 2.0, Exercises: 2.0, Deeper Learning: 1.8.
Chapter 12: Rigid Transformations

See standard error chart for the review scoring

Reviewer Comments (Learn more)

Moderate (2.2)

Comments/Ideal Use:

Overall this is a very unique idea with much potential. A lot of thought and research has gone into this resource! Very nice pieces under DETAIL RESOURCE PRACTICE tabs once I was in to the RIGID MOTION sections. The instructor has at least 12 modalities to choose from within these tabs and most of them are interactive.

The instructor must have access to devices for all students to achieve the full functionality of this curriculum. Novice teachers would probably be better suited due to their desire to think "outside the box" in regards to alternative ways to facilitate content. The teacher must be technology savvy and willing to "tinker" otherwise this is not for you. Don't expect to pick this up and implement without at least 3-4 hours of viewing the instructional webinars.


  • The lack of one ALL ENCOMPASSING teacher guide for this particular Flexbook. I could only find bits and pieces of teachers editions. I would find an edition with one chapter but not the entire student edition - the teacher must include all of the text that the student guide contains.


  • There are so many features: Flexbook concept, modalities, editing, publishing, etc, this could be a negative, in that many people are not aware of all of the capabilities. The developer has an ingenious idea and needs to get the webinars/training videos out of the "Attribution Guide" at the bottom of the page and "plaster" it in a more viewable area. Otherwise people will never know about the functionality of this resource.
  • Link the teacher edition to the student edition somehow so the viewer will find them simultaneously.
  • I would recommend incorporating some response to the instructor with student scores from interactive assessments.
  • Make a teacher edition with all of the student text.

Comments/Ideal Use:

I have taught a traditional classroom for decades, and am reluctant to change. Reviewing this Flexbook has opened me to possibilities in teaching and learning I had not fully considered. I applaud your efforts.

The ideal use of this resource is as a support resource to current curricula. Some of the content presentations are much better than other materials on the market. It would be best if the teacher using any of this material were experienced, and had knowledge of the CCSS practice standards, as they are now explicitly missing from the lessons. The resources available to teachers are hard to find or navigate, even for those with a strong interest in a technology driven curriculum.


  • No answer keys for problem sets.
  • No unit (chapter) assessments and very limited mid-unit assessments.
  • No number/symbol references to Common Core content standards in lessons - many teachers are required to provide these connective numbers to lesson objectives for district.
  • No reference at all to the CCSS Math Practices Just as important in our district as the content standards.


  • Provide answer keys - makes the teacher job less overwhelming, especially new teachers.
  • Develop printable quizzes and exams for each unit. (With answer keys, of course) - helps teacher match learning with letter grade assigned, and appropriate for student feedback.
  • Write the standards addressed by each lesson at the top of each lesson.
  • Make specific references, particularly in a teacher edition.

Comments/Ideal Use:

Within a classroom with the opportunity for class discussion, trained teacher with continuous PD for help with content and tech if needed.


  • Connection/difference between a Flexbook and individual concepts interaction
  • Material not at high school geometry level - grade 6-8 standards within object
  • Assessments in Flexbook - rubrics, answer keys missing


  • Clarify, enable, fix interaction between Flexbook and concepts
  • Use the high school geometry standards to identify content
  • Include assessments

Comments/Ideal Use:

The issue with this site is that it is student focused. A teacher could use this as a supplement for their class but if the teacher were to use this as a primary teaching tool they would have to spend many hours on each lesson structuring the lessons so they could be taught. Now a teacher could have a student working on the lessons as a self directed activity. If a parent is homeschooling their child, this could be an excellent way to help a student gain an understanding of Geometry.


  • The interactive practice questions are excellent but there could be more interactive activities like in chapter 1 where the student was able to determine whether the points were part of a line. The more interactive activities the better the student will understand the concepts.

Comments/Ideal Use:

This could be used for home instruction as a review of geometry concepts at the end of the year in a middle school framework. It could also be used for a brush up at the end of the year to begin to review for the EOC test in Washington.


  • Learning objectives are not identified.
  • Far too much of the work is a review of material covered in grades 7 and 8, not an extension, not more complex, not deeper, and not a lot of new material.
  • Difficult to find engaging applications, or any real applications in the unit. Modeling is nonexistent.
  • It does not provide extra support for students working AT or ABOVE grade level.


  • Learning objectives matched to the CCSS could be added.
  • Repackage this as suitable for grades 7 and 8. Or as a review of geometry before embarking on high school geometry.
  • Add applications suitable for CCSS. Add modeling problems.

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