This chapter examinse how the mechanisms of structuring and problematizing are sometimes complementary and sometimes in tension in design, discuss design tradeoffs in developing scaffolded investigation tools for learners, and consider the reliance of scaffolding on a classroom system of supports. It presents an analysis of two general mechanisms to characterize how scaffolded tools can support learning. The chapter describes how these dual mechanisms can address the challenges learners face by structuring tasks to make them more tractable and to shape tasks for learners in ways that makes their problem solving more productive. It describes the argument for these mechanisms by first considering how tools affect the experience of tasks for learners. The chapter reviews some of the critical challenges learners face in complex domains such as science and mathematics learning. It considers how the mechanisms can interact and discuss issues of the embedding of tools in classroom contexts.