The purpose of this research were to: 1) develop scientific activity packages on plant lives for using in the substance learning group of science 2) develop scientific critical thinking skill by using the inquiring teaching method for Prathomsueksa 4 students    3) compare academic achievement on scientific critical thinking skill of Prathomsueksa 4 students  before and after using scientific activity packages.
The sample of this study were 25 Prathomsueksa 4 students of Watkatesamosorn School, Amphoe Bangnamprieo, Chachoengsao Province.The Tools used for data collection were 1) scientific activity packages used for the development of scientific critical thinking skills 2) a test format on science learning by using scientific activity packages and 3) a test format on scientific critical thinking skills of students taught by using scientific activity packages.The statistics used in data analysis were mean, percentage, and standard deviation. 
The results of the study were as follows:
1. The efficiency of scientific activity packages was higher than the specific efficiency criteria.
2. The achievement in science learning by using scientific activity packages was higher than before using the packages and was statistically significant at .05 level
3. The critical thinking skill of the students taught with scientific activity packages were higher than before using the packages and was statistically significant at .05 level
