The study utilized the quasi-experimental model with a post-test control group, and
its sampling was 37 pre-service teachers studying their second year at Uludağ University, Science
Education Department. An assessment instrument of 28 questions including multiple choice and
open ended questions on 11 process skills was used in the study. As a result, it has been noticed that
there were not significant differences in view of total scientific process scores between the test group
and the control group; however, it has been seen that the pre-service teachers in the test group, who
were taught the biology lessons with the Project Based Learning Method, were more successful than
the pre-service teachers in control group in developing their process skills of estimating,
hypothesizing and examining, determining and changing the variables, measuring, numeral and
spatial correlating, data recording, test designing, and interpreting. Nevertheless, in the test group,
no development has been seen on the process skills of classifying, observing, and data interpreting