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Categorical thinking is the underlying capability of information technology. In order to get more understand the development of children categorization ability, two experiments were employed in this research. 60 children (30 boys, 30 girls) joined the experiment , there are 20 children for each age group(3-4 years , 4-5 years, 5-6 years). In experiment1 children were asked to categorize the pictures freely; in experiment 2 children were asked to categorize based on the given example.The result showed that most 5-6 years old children categorize based on taxonomic rules, while younger children more categorize based on similarity and thematic relationship. This result showed that children's thinking developed form surface similarity to essential connection. The way of the categorization (free/forced) more influenced the 3-4 years children, in the free categorization 10% of them can't categorize the picture, but all the children can do the categorization in the forced task. This result showed that younger children's thinking flexibility was not fully developed, they need a clearly introduction to help. Based on the results above, education suggestions were given that children be trained based on their age characteristics and critical period should be grasped in thinking development, so that can help develop their information technology literacy.

In this paper, we propose a new geometrical two-erose-ring scattering model for the multiple-input multiple-output (MIMO) mobile-to-mobile (M2M) fading channels. In this model, the line-of-sight (LOS) and non-line-of-sight (NLOS) components are all considered. Based on the geometrical model, a reference model and the corresponding simulation model are derived. Their statistical properties such as the three-dimensional (3D) space-time cross-correlation function (CCF), the two-dimensional (2D) spatial cross-correlation function (2D spatial CCF), and the temporal autocorrelation function (ACF) are studied. For computing the parameters of the simulation model, the extended method of exact Doppler spread (MEDS) are used. The close agreement between the statistical properties of the simulation model and those of the reference model are demonstrated. We believe that this research work is important for designers to develop, analysis, test, and optimization the future MIMO M2M communication systems.