Mathematical knowledge for teaching (MKT) is a professional knowledge crucial for effective mathematics instruction, encompassing both content knowledge (CK) and pedagogical content knowledge (PCK). The purpose of this study is to investigate the hierarchical structure of PCK for fractions by seeking further evidence for the PCK-Fractions assessment. The PCK-Fractions measure is designed to examine the effectiveness of teacher education program and field experiences in facilitating preservice teachers' (PSTs) PCK for children's fraction reasoning in grades 4-6. Emplying 165 undergraduate students, the research investigates how different levels of coursework and field experience influence PCK-Fractions scores. Results suggest that both completing coursework in a teacher education program and having grades 4-6 field experience each led to higher PCK-Fractions scores. Additionally, this study provides further evidence supporting the validity of the PCK-Fractions measure as a reliable indicator of PSTs' proficiency in teaching fractions. Implications for mathematics teacher education and educational research are discussed.