Scheme it's far easier to grasp. With SICP you basically rewrite a Scheme within a Scheme. And you teach Calculus to the interpreter to solve further problems.
Online SICP: http://sarabander.github.io/sicp/
I fondly remember doing a course in my CS degree that was basically working through SICP as a class, taught my an ancient but very fun and enthusiastic tenured professor. When he retired I think the curriculum was updated to JavaScript (??) or as the new professor called it "scheme in drag". I'm glad to have taken the original course..