Vary your assessments and retrieval exercises.
From Diversifying Economic Quality: A Wiki for Instructors and Departments
Sources:
Glover, J. A. (1989). The "testing" phenomenon: Not gone but nearly forgotten. Journal of Educational Psychology, 81, 392-399. Click here to access the study.
McEachern, William A. "THE TEACHING ECONOMIST." The Teaching Economist. Cengage Learning, 2008. Web. 10 June 2011. <http://www.cengage.com/economics/mceachern/theteachingeconomist/issue_34/index.html>. Click here to access the article.