The following terms are developed and/or defined in this grade level's materials.

ACUTE TRIANGLE  EXPONENT  PRISM 
ADDITION (DECIMAL)  FOOT (MEASUREMENT)  PRISM (VOLUME) 
ADDITION (FRACTION)  ISOSCELES TRIANGLE  PROBLEM SOLVING 
BASE (EXPONENT)  LCD (FRACTION)  PYRAMID 
BASE (POLYHEDRON)  LCM (WHOLE NUMBERS)  QUADRILATERAL 
CALCULATOR  LCM (FRACTION)  RECTANGLE 
CAPACITY (VOLUME)  METRIC UNITS  RECTANGULAR PRISM 
COMMON FRACTION  MULT. PROPERTIES  REMAINDER (DIVISION) 
COMPOSITE NUMBER  MULTIPLICATION (DECIMAL)  RIGHT TRIANGLE 
CONE  MULTIPLICATION (FRACTION)  SCALENE TRIANGLE 
COORDINATE  MULTIPLICATION (WHOLE)  SIMPLEST FORM 
CUBE  NATURAL NUMBER  SPHERE 
CYLINDER  ORDER OF OPERATIONS  SQUARE 
DECIMAL  ORDERED PAIR (COORDINATE SYSTEM)  SUBTRACTION (DECIMAL) 
DECIMAL NOTATION  ORIGIN  TIME 
DISTRIBUTIVE (WHOLE)  PARALLELOGRAM  TRAPEZOID 
DIVISION (DECIMAL)  PLACE VALUE (NUMBERS)  UNKNOWN 
DIVISION (WHOLE)  PLACE VALUE (DECIMAL)  VARIABLE 
DIVISION BY TEN  POLYGON  VERTICES (SOLIDS) 
EQUILATERAL TRIANGLE  POLYHEDRON  VOLUME 
EQUIVALENT DECIMAL  POWER  WEIGHT 
ESTIMATION (DECIMAL  POWERS OF TEN  
EXPANDED FORM  PRIME NUMBER  
  
  
  
  
  
The following terms appear in this grade level's materials. At this grade level the terms are used in the lesson proper in examples or illustrations.
The purpose here is to reinforce understanding of the terms.

ARRAY (MULT.) (WHOLE)  FACTOR  NUMBER LINE (FRACTION) 
ASSOCIATIVE (ADD.) (WHOLE)  FACTOR (WHOLE)  NUMBER SENTENCE 
AXES  FACTOR TREE  NUMERATOR 
BAR GRAPH  FRACTION  ORDERING 
CENTIMETER  FRACTION TO DECIMAL  ORDERING DECIMALS 
COLLECTING  FREQUENCY TABLE  PROPERTIES (FRACTION) 
COMMUTATIVE (ADD.)  GRAPH  PROTRACTOR 
DEGREE (ANGLE)  GRAPHING  RENAMING (FRACTION) 
DEGREE NOTATION  IDENTITY (ADDITION)  ROUNDING DECIMALS 
DENOMINATOR  IDENTITY (MULT.)  SEQUENCE 
DIVISION (FRACTION)  INCH  SUBTRACTION (FRACTION) 
DIVISION WITH DISTRIBUTION  KILOMETER  SYMBOLS FOR DIVSION 
DIVISOR, QUOTIENT  LENGTH  SYMBOLS OF GROUPING 
EQUATION  LIQUID MEASURE  TENTHS, HUNDREDTHS 
EQUIVALENT FRACTIONS  LOCATING POINTS  THOUSANDTHS 
ESTIMATING PRODUCTS  MEASUREMENT  THREE DIMENSION 
ESTIMATING QUOTIENTS  MEASUREMENT (ANGLE)  TRIANGLE 
EXPANDED FORM (DECIMAL)  MULT. AND DIVISION  WHOLE NUMBER 
FACE (POLYHEDRON)  MULTIPLE  
  
  
  
  
  
A synonym of the following terms are used. The synonym helps to bridge the learner's non mathematical experiences to mathematics terms that will more formally be worked on.
A synonym may also be used because these historical terms may have been replaced by a new vocabulary (k12math.info's list of 1,000 terms has not changed in 40 years).
Wiktionary dictonary may help here.

APPLICATIONS (FRACTION)  INEQUALITY (FRACTION)  UNIT VOLUME 
COORDINATE SYSTEM  MIXED NUMERAL (FRACTION)  WORD PROBLEM (DECIMAL) 
ENGLISH UNITS  MULT. BY GROUPING  WORD PROBLEM (FRACTION) 
GCF (WHOLE NUMBERS)  RELATION TO DIVISION (FRACTION)  WORD PROBLEMS (WHOLE) 
INEQUALITY (DECIMAL)  UNIT AREA  
  

K12math.info selected the content that appears here. All terms appear in the lesson proper. 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 and how they are to be developed in the lesson proper. These terms need to be used in examples, illustrations, class activities and homework to help further understand them.
Resources:
Learners age 5 to 11 Grades K through 6 (from Wikieducator's "Come fly with me..." project).
Teaching OER Mathematics.
Learning design a Wikieducator.org project.
Additional observations made while collecting information for this site on unit development in a textbook:
 One type has a chapter unit divided into 3 parts:
Part 1 has a written explanation of the concept being developed (or defined).
Part 2 has examples and illustrations of the concept.
Part 3 classroom and/or homework activities.
 Another approach consists of 2 parts:
Part 1: the concept being developed (or defined) is being used in several carefully designed examples and illustrations.
Part 2: classroom and/or homework activities.
