Abstract This research is aimed to identify students difficulties in learning basic concept of natural science based on the difficulty level and absorbability of test items. The main data used is students’ response at essay test for Basic Concept of Natural Science for the PGSD students.

The obtained data can be analyzed by quantitative-descriptive approach using absorbability at classic test theory approach and difficulty level of Rasch model at the items of response theory approach. The research results that (1) students’ struggle in learning basic concept of natural science based on absorbability may cover 78,55% of whole materials which are mastered by the students. (2) Material for Basic Concept of Natural Science Subject, especially energy, is presumably difficult. It may be analyzed by test items response theory approach. (3) Students’ struggle in learning science based on absorbability covers 68% of whole materials mastered by the students. (4) Material for the science subject which is presumably difficult acknowledged by item response theory approach is energy material which is integrated with surround environment.

Keywords: learning struggle, basic concept of natural science, PGSD, absorbability, difficulty level of item test