Terms 
Projected CK12.org math textbook content 
Existing textbook content 
>>>>> Grade level >>> 
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>>> Average Age >>> 
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CIRCLE  3  4  3    3    3  4      4  4 
CURVE    3    3                 
ARC                      3  3 
CENTER    3  3    3      3      4   
CENTRAL ANGLE                      4   
CHORD                      4  4 
CIRCUMFERENCE              4           
COMPASS    3  3    3               
CONCENTRIC CIRCLES                      4   
DIAMETER              4  4      4   
ELLIPSE                        4 
INSCRIBED                      3   
INSCRIBED ANGLE                      4   
ON THE CURVE    3                  2   
RADIUS    3     3    4  4      4   
SECANT                      4   
SECTOR                        3 
SEMICIRCLE                3      4   
TANGENT LINE                      4   
>>>>> Grade level >>> 
K 
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PLANE                    3  4  3 
COPLANAR POINTS                      4   
HALF PLANE                  3  3     
INTERSECTING PLANES                      3   
POLYHEDRON            4  4        4   
ALTITUDE (POLY.)                      3   
BASE (POLYHEDRON)            4  3        3   
CONE  3  3  3      4  4  4      4  4 
CONIC                        4 
CUBE  3  3  3      4  4  4      4   
CYLINDER  3  3  3      4  4  4      4   
EDGE (POLYHEDRON)      3        4  4      4   
EULER'S FORMULA                      4   
FACE (POLYHEDRON)    3  3      3  4  4      4   
GREAT CIRCLES                      4   
LATERAL FACES                      4   
>>>>> Grade level >>> 
K 
1 
2 
3 
4 
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7 
8 
9 
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11 
NETS (POLYHEDRON)              4  4      4   
PRISM            4  4  4      4   
PYRAMID            4  4  4      4   
RADIUS (SPHERE)            3          4   
RECTANGULAR PRISM    3  3      4  3  3         
REGULAR POLYHEDRON                      4   
RIGHT PRISM                      4   
SOLID    3  3      3  4  3         
SPACE                      4   
SPHERE  3  3  3      4  4  4      4   
TETRAHEDRON                      3   
THREE DIMENSION  3  3  3      3  3  3      3   
TRIANGULAR PRISM              4  3      3   
VERTICES (SOLIDS)    3  4      4  4  4      4   

Useage codes:
4 Definition or formal development
3 Term present
2 Synonym used
1 Enrichment
 Term not present
K12math.info selected the content that appears in the k through 5th grade columns. The selection process is based upon a content analysis of 2013 to advance copies of 2015 student mathematics
textbook series. Series that base their content on 2010 and/or 2012 standards. The analysis also included content that was felt would be needed for the
transistion to CK12 existing textbook series.
Editor's Note: This is a very basic outline of the content, its distribution and how the terms would be developed in the lesson proper. In actually writing additional terms maybe used (only 674 terms of k12math.info list of 1,000 are used),
the grade level distribution could be altered (careful as standards are often used to position terms) and how the term is used for a given grade level.
Also note with the development of the k5th grade materials, adjustments in the existing materials maybe needed.
Content, content distribution and how the content is used in the 6th through 11th grade columns are based on content in the existing CK12.org student math textbooks:
CK12 Middle School Math  Grade 6 CK12 Foundation.
Date Created: Feb 22, 2012  Last Modified: Jan 07, 2014
CK12 Middle School Math  Grade 7 CK12 Foundation.
Date Created: Feb 22, 2012  Last Modified: Oct 01, 2013
Basic Algebra (Grade 8) CK12 Foundation.
Date Created: Feb 22, 2012  Last Modified: Oct 01, 2013
Algebra I  Second Edition (Grade 9 ) CK12 Foundation.
Date Created: Feb 23, 2012  Last Modified: JAN 09, 2014
CK12 Basic Geometry Concepts (Grade 10 ) CK12 Foundation.
Date Created: Feb 24, 2012  Last Modified: Nov 12, 2013
Eleventh grade:
 CK12 Trigonometry  Second Edition CK12 Foundation.
Date Created: Feb 23, 2012  Last Modified: Nov 14, 2013
 Basic Probability and StatisticsA Full Course CK12 Foundation.
Date Created: Feb 23, 2012  Last Modified: Oct 01, 2013
 CK12 Math Analysis CK12 Foundation.
Date Created: Feb 23, 2012  Last Modified: Oct 10, 2013
Note: Complex numbers and Vectors were covered in both Trigonometry and Math Analysis materials. The trigonometry approach was used as the primary source. Those who want to check the approach taken in the Math Analysis materials may click on Complex Number or Vector.
