I would start with Dr Scheme (now called Racket/PLT Scheme). That is what CS301 at UT Austin started with https://plt-scheme.org/ https://plt-scheme.org/ back

I would start with Dr Scheme (now called Racket/PLT Scheme). That is what CS301 at UT Austin started with https://plt-scheme.org/ https://plt-scheme.org/ back when I was an undergrad in 2000