The teaching and assessment of physical activities in physical education often includes the use of written and/or video-based activities, especially for the knowledge and understanding components (Oslin, Mitchell and Griffin, 1998; Antoniou, Derri, Kioumourtsoglou and Mouroutsos, 2003). The purpose of this study is to investigate the impact of written and video-based knowledge assessment tools on two teaching environments in the context of athletics. Content knowledge of rules, planning tactics and techniques in athletics was taught in two experimental teaching units (ETUs). The ETUs represented two teaching environments, namely: practice and handouts (n=200); and class sessions (n=200). The subjects were 12-13 year olds, and completed a pre-test and a post-test for both a written paper (WP) and a video-based paper (VP). More specifically, the aim of this research was to assess: (i) which of the two teaching environments contributed most to learning; (ii) whether the written and video-based assessments communicate the same assessment information in relation to the teaching environment; and (iii) whether content knowledge, such as techniques, planning tactics and rules, taught in a practical performance teaching situation adequately prepares students for written and video-based assessments.In the pilot study on 49 subjects (van Vuuren- Cassar and Lamprianou 2003), Rasch model analysis suggested that the WP and the VP tests were uni-dimensional and reliable (R=0.86 to 0.92). The subjects of the class-based teaching environment achieved statistically significant (p=0.05) better scores on rules (M=24.21; SD=3.58; Range=0- 30), planning tactics (M=19.00; SD=6.37; Range=0-30), and techniques (M=20.67; SD=16.18; Range=0-40), when video- based assessments were used. The findings of the pilot study suggest that a WP and a VP assess different competencies on the same test items. Students familiar with video analysis will cope satisfactorily with video-based assessments. The main study will be carried out over the 10 week period (including Easter recess) between February and April 2005. Trained novice teachers will be delivering the ETUs. The main study will report on (i) which of the two teaching environments contributed most to learning; (ii) whether the written and video-based assessments communicate the same assessment information in relation to the teaching environment; and (iii) whether content knowledge, such as techniques, planning tactics and rules, taught in a practical performance teaching situation adequately prepares students for written and video-based assessments.Antoniou, P., Derri, V., Kioumourtsoglou, E., and Mouroutsos, S. (2003). Applying Multimedia computer- assisted instruction to enhancing physical education students' knowledge of basketball rules. European Journal of Physical Education, 8 (1), 78-90.Oslin, J.L., Mitchell. S.A., and Griffin, L.L. (1998). The game performance assessment instrument (GAPI): Development and preliminary validation. Journal of Teaching in Physical Education, 17(2), 231-243.Vuuren-Cassar, van G., and Lamprianou, I. (2003 ) Validation of Written and Video Based Assessment Instruments in Physical Education, Journal of Maltese Educational Research, 1(2), 15-34. [On- line]. Available: http://www.educ.um.edu.mt/jmer/ (31 January 2005)