Understanding the basics:
What is glass?
https://videos.bullseyeglass.com/videos/what-is-glass/ (video)
How is glass made?
field-guide_-how-glass-is-made.pdf (PDF guide)
Why is glass transparent?
https://ed.ted.com/lessons/why-is-glass-transparent-mark-miodownik
What is fusing?
http://www.bullseyeglass.com/what-is-fusing.html
What is slumping?
http://www.bullseyeglass.com/what-is-slumping.html
What is tack fusing?
http://www.bullseyeglass.com/what-is-tack-fusing.html
Building skills:
Heat and glass
https://www.bullseyeglass.com/methods-ideas/technotes-4-heat-a-glass.html
Get a reaction
http://www.bullseyeglass.com/methods-ideas/get-a-reaction-bullseye-reactive-glasses.html
Reactive Potential of Bullseye Glass
http://www.bullseyeglass.com/methods-ideas/glass-reactivity-chart.html (chart)
Improve your cutting
http://www.bullseyeglass.com/methods-ideas/improve-your-cutting.html
Kilncarving
https://videos.bullseyeglass.com/videos/kilncarving/ (subscription required)
Making parts sheets
https://videos.bullseyeglass.com/videos/making-part-sheets/ (subscription required)
Hands-on projects:
Linear reaction
http://www.bullseyeglass.com/methods-ideas/make-it-linear-reaction.html
River Rock reaction
http://www.bullseyeglass.com/methods-ideas/river-rock-reaction.html
More to explore:
Chemistry of Glass
https://www.cmog.org/article/chemistry-glass (chart)
Glass Dictionary
https://www.cmog.org/research/glass-dictionary
Holy Frit
https://vimeo.com/489473689 (documentary film trailer)