This study draws on data from a broader video-stimulated interview study of the role of optimism in collaborative problem solving. It examines the activity of a Grade 5 student, Tom, whose initial constructing activity resulted in a "Partially Correct Construct". Insistent questioning from another group member pressuring for clarification led to Tom developing a "more correct construct" with further potential for revision. This paper raises questions about influences that can stimulate or inhibit construct refinement. (Contains 3 tables.) [For the complete proceedings, "Shaping the Future of Mathematics Education. Proceedings of the Annual Conference of the Mathematics Education Research Group of Australasia (33rd, Freemantle, Western Australia, Australia, July 3-7, 2010)," see ED520764.]