It Works Both Ways: Transfer Difficulties between Manipulatives and Written Subtraction Solutions

Table 1

Experiment  1 design.

	𝑛	Pretest	Practice test 1	Practice test 2	Posttest
Control (no instruction)	10	Written	Written	Written	Written
Written instruction	10	Written	Written	Written	Written
Manipulatives instruction	10	Written	Manipulatives	Manipulatives	Written