Where can I find out what the drag and drop items are for all the code the guy in the tutorial is using?

https://www.packtpub.com/sites/default/files/downloads/4100OT_Appendix_Drag_and_drop_Icons_to_GameMaker_Language_Reference.pdf

Yes you can use drag and drop only, to make good games with game maker.

i have been teaching kids in school and we go on to bag a couple of championships in inter-school competitions.

A few basic coding will help greatly but not necessary. Cheers.

GameMaker was my first game dev environment. I used drag-and-drop for about a year (this was at age 10, btw) and found the coding obtuse and intimidating so I avoided it entirely. One day on a whim I decided to ditch D&D for scripting entirely, and the transition was seamless. Didn't even have to read a single tutorial.

If an 11-year old can do it, you can do it. Don't feel rushed to transition because D&D concepts use same foundation of boolean logic that you'll be using in code, but at the same time don't feel so daunted that you never try.

Please do not necro year-old posts.