Use the Following Description of a Controlled Experiment

Essay

Use the following description of a controlled experiment:
Two similar kindergarten classrooms, each containing 20- 25 students, have agreed to participate in a study to see if incorporating math manipulatives into the teacher's lesson improves understanding of new concepts in geometry, like recognizing shapes and similarities in shapes. The teacher in one classroom gives a standard lesson without the use of manipulatives then gives a three- question quiz about the new geometry concepts that were taught. The teacher in the second classroom gives a geometry lesson that incorporates the use of math manipulatives. The same three- question quiz is given and the scores of the two classrooms are compared to see whether the use of math manipulatives improved quiz scores.
-Which features of a well- designed control experiment does this study have? Which features are missing?