What Is the Primary Reason for Delaying the Use of Nonproportional

Multiple Choice

What is the primary reason for delaying the use of nonproportional models when introducing place-value concepts?

A) Models do not physically represent 10 times larger than the one.
B) Models like abacus are hard to learn how to use.
C) Models like money provide more conceptual than procedural knowledge.
D) Models do not engage the students as much as the proportional models.