This study examined the effects of an instructional procedure designed to teach both field-dependent and field-independent sixth graders to control variables and to transfer this ability to novel tasks. Students were randomly assigned to either a treatment group taught with a special instructional procedure adapted from Case or a group where students freely explored science equipment without receiving feedback. Three posttest tasks administered approximately four weeks after the last training session served as retention and transfer measures. Results indicated that students receiving the special instructional treatment correctly tested significantly more variables on the posttest tasks than did students in the other group. Within-group analyses revealed that the special treatment was effective for field-dependent as well as field-independent students, while the other treatment was effective for only field-independent students.