My working hypothesis is that students with “more” experience in a subject area are going to have an easier time of constructivism which relies so much on the student’s initiative to drive progress. Additionally, students with a higher commitment to their subject area, and who understand the rationale for constructivist approaches may do better.
Specific (hypothetical) strategies to help struggling students might include starting with group work, in which some group members are not struggling (with constructivism); encouraging struggling students to investigate the rationale for constructivism so that they gain a greater understanding of the reasons for the approach; and providing more opportunities for checking their work (replacing a structure that is typically present in objectivist assignments) such as open-door office hours with instructors, and a detailed rubric.
A conducive environment would be one in which the transition to constructivism is slow and logical, and where SMEs (professors, librarians) are willing (proactive even?) to assist students as guides and cheerleaders. In younger students (i.e. early elementary) a conducive environment would include making the work fun. In all cases my hypothesis is that early attempts should be low-pressure situations in which students are free to explore without worrying about grades.