The purpose of this study was to find how the teacher could help students formulate scientific hypotheses. Data came from two microteaching episodes in which two groups of pre-service secondary science teachers taught high school students as they were engaged in abductive inquiry activities of earth science. Multiple data sources including video recordings of the microteaching, the pre-service teachers' oral and written reports, student worksheets, and instructional materials were examined. The analysis identified four categories of teaching strategies which could be used by science teachers to help students in hypothesis-generating inquiry. These included: (1) "expanding and activating students' background knowledge", (2) "providing analogies", (3) "questioning", and (4) "encouraging students to use alternative forms of representation". Implications for science education as well as for further research are suggested. (Contains 3 figures.)