摘要:The aim of this study is to find out how pupils will connect their observations and explanations from a demonstration. Seventh graders (117) were shown successively two demonstrations about floating and sinking. Pupils’ observations and explanations were classified and compared with each other in the two demonstrations. The four observation categories were: Complete observation, incomplete observation, non-essential observation, and no observation. The five explanation categories were: Scientific explanation (density), alternative explanation (weight), situational explanation (temperature), spontaneous explanation (irrelevant, insufficient, wrong), and no explanation. Both the observations and the explanations were improved significantly in the second demonstration even that no teaching was done between the demonstrations. The ways used by the seventh graders in processing their observations and explanations have been examined from the viewpoint of perceptual learning, variation theory, and the memory models in cognitive psychology.