Two points: 1) Scheme is really really simple to learn. If learning a new language is a major obstacle, you will not be able to finish the course anyway, since

Two points: 1) Scheme is really really simple to learn. If learning a new language is a major obstacle, you will not be able to finish the course anyway, since it includes implementing multiple small languages. 2) Some of the tasks would be nearly impossible in Python (or any other non-homoiconic language). One exercise is implementing a metacircular evaluator. To do this in Python would require you to implement scanner, parser etc - a major undertaking.