The CA standard used to design this lesson is quoted below. Since we are dealing with fourth grade, care had to be taken to use appropriate words and to present concepts in an appropriate way. The weblesn is kept light by the use of the talking answer wizard
and the use of kid friendly websites. This standard is mostly about definitions. The talking professor, 
, the wiz and other characters move things along. Part 3.6 of the standard is not addressed because it calls for actual construction of models of solids. The material presented in this weblesn is fundamental to all further study of math and should be mastered by the student.