With five gifted and nine average elementary school students, this study attempted to make a comparative analysis on the characteristics of their scientific writings for earth science-related topics. The analysis found that all of the gifted students showed higher scores than the average in the writing sections of scientific nature, logical nature and creativity. Compared to the average scores, their creativity scores were far higher. By comparing and analyzing the predicates in the writings two groups wrote, I found that the gifted students used more sentences per topic than the average students. Both groups wrote the most numbers of sentences for Volcano-related topics. In the meantime, the gifted children used the least numbers of sentences for the related topics to atmospheric pollution and the average students did so for the related topics to fossils. By the analysis on the patterns of predicate, it was observed that both groups used material predicates most and verbal predicates least. As far as the second most used predicates are concerned, the gifted children used relational predicates and the average students used mental predicates.