Аннотация:Testing ancient technologies (by the procedures of text analysis and hands-on experiments) is a feasible way to scaffold students’ future promotion in Natural Sciences. This idea became our major hypothesis as we strived to develop a propaedeutic Natural Science curriculum within the Developmental Instruction framework. A student, thus, can acquire the desired concepts through his own activity: these concepts are the guidelines of ancient technologies. One assimilates them through reflection, while he reconstructs these ancient technologies - using special texts devised to serve the purpose. The curriculum builds upon the “spiral” way of developing student’s activity: “text – basic model – experiment – model correction – text”. Our students’ future efficiency in Chemistry compared to that of the control group is analyzed to support our hypothesis. Though both groups are equal in doing Math test, they differ significantly in Chemistry: the experiment groups (we had three cycles, two groups each) perform better.