Is he unschooling or are you looking for curriculum?
Chemistry and biology have a ton of interesting self-exploration resources out there (I'm a huge fan of self instruction.) Instructional videos are hit and miss, my DS8 when doing his own explorations will search for videos and screen them for whether he likes the depth and detail. When he hits a lecturer he likes he'll watch a number of their videos.
For some intuitive experimental stuff:
"Foldit" is a protein folding simulator where solving the folding of proteins is crowdsourced (lots of subtle deep learning here)
On the iPad, "Chemist-Virtual Chem Lab" has a tremendous range of chemicals and interactions available for experimenting.
Can't go wrong with a weekly subscription to "ScienceNews" as articles can easily springboard thinking/researching into other topics.
For some crazy stuff, the Youtube channel "VSauce" has some really neat probative science stuff. Sometimes it leans a little old, but neat ideas.
