The purpose of this research is to find out
the practicality and effectiveness of student worksheet
using IBL assisted by basic mathematics skills to
develop critical thinking skills. The method used was
quasi-experimental designs with pretest-posttest type.
The practicality was obtained through the results of
observations of the learning implementation and
student responses questionnaire. The effectiveness was
obtained through pretest-posttest data analyzed by N-
gain and effect size. The results of the observation of the
learning implementation and student responses
questionnaire were included in very good and very high
categories. N-gain test in control and experiment groups
was considered in low and medium categories. While,
the effect size obtained was in very strong category. In
general, the result shows that the student worksheet has
met the criteria of practicality and effectiveness.
Keywords : Student worksheet, IBL, Mathematic Skills, Critical Thinking Skills.