The results indi cate: (1) According to the error analysis before the point of strategy discovery , in the early period of strategy discovery in figure reasoning, the metacogniti ve mechanism plays the main role.

The results are as follows: from the source of change, experimental manipulation is a important source of strategy discovery in figure reasoning task; from the variability of change, children are followed learner model of strategy discovery; from the path of change, the main error are orientation err and size err in all three groups.

Prioritized admission strategies for the client requests in the VOD server;