This self-study conducted using teaching experiment methodology (Steffe & Thompson, 2000) examined high school students' retention of mathematics and science concepts. While there were differences between the mathematics and science classrooms, both studies used entrance and exit slips as primary forms of assessing short-term retention. Unit tests functions as assessment for long-term retention. The findings show that a variety of teaching strategies benefited students' retention of concepts in both mathematics and science. Results from these teaching experiments contribute to the expansion of limited research on students' retention of mathematics and science concepts.