Mayer's concern is how one applies discovery-based teaching techniques. He provides empirical research as evidence that discovery-based teaching techniques are inadequate. Here he cites this literature and makes his point "For example, a recent replication is research showing that students learn to become better at solving mathematics problems when they study worked-out examples rather than when they solely engage in hands-on problem solving. Today's proponents of discovery methods, who claim to draw their support from constructivist philosophy, are making inroads into educational practice. Yet a dispassionate review of the relevant research literature shows that discovery-based practice is not as effective as guided discovery."