Three observational studies of student learning from classroom experience in science and social studies in elementary and middle school classrooms were carried out. Immediately after the administration of the short-term and long-term (12 months) achievement tests, selected students were asked to describe how they answered each item and to recall relevant learning experiences. Students reported basing their answers on recall of classroom learning experiences for 30%–50% of the items and deducing the answers from related experience and knowledge for 15%–24%. Item-answering processes were affected by length of time between learning and test administration, the nature of the topic studied, the students’ background knowledge, type of learning experience, and involvement in classroom activities. A model is described that explains how students use their multilayered episodic and semantic memory for relevant learning experiences and related knowledge to answer achievement test items. Item content and structure defines the domain within which students apply complex metacognitive, retrieval, deduction, and knowledge construction skills.