The effect of the timing of instructional support in a computer-supported problem-solving program for students in secondary physics education. - Henk J. Pol; Egbert G. Harskamp; Cor J. M. Suhre (Comput. Hum. Behav., 2008)

How indirect supportive digital help during and after solving physics problems can improve problem-solving abilities. - Henk J. Pol; Egbert G. Harskamp; Cor J. M. Suhre; Martin J. Goedhart (Comput. Educ., 2009)