A classroom observation rating scale, based upon a recent analysis of the literature and conceptually verified by open education advocates, effectively differentiated British and American open classrooms from American traditional classrooms. The influence of socio-economic settings was also demonstrated. For the three comparison groups, more features of open education were found in higher socio-economic settings than in lower ones. Rater-reliability for the classroom observation measure was high. The classroom observation rating scale is recommended as a survey instrument in a school system that is beginning to experiment with open education. Baseline data can be gathered and the measure can be repeatedly used to chart changes in classroom practices. A teacher questionnaire, parallel in form to the classroom observation rating scale, may be used in workshops as a starting point for a dialogue about teaching. Both measures can be considered as initial steps in adding greater theoretical precision and empirical understanding to the concept of open education. (Author)