I'll second that, having learned much of the basics myself on one of the greatest patchables in history, the ARP 2600. Having the prepatched signal paths was very useful inasmuch as I could see what a "conventional" flow was capable of, and also what patched changes to those signal paths might do. The 2600 in question here was located in Middle TN State's Electronic Music Studio through part of the 1970s and much of the 1980s, and I don't think a better educational analog synthesizer has been created since the 2600. It's something that Korg, through their ties with David Friend of ARP, should still consider reissuing, IMHO.
Good patchables for learning the modular basics that you can get these days include:
Moog: Mother32, DFAM, Grandmother.
Korg: MS-20 mini + SQ-1.
MakeNoise: 0-Coast (excellent for understanding West Coast concepts, btw)
Arturia: MiniBrute 2 and 2S (the 2 is keyboard-based, while the 2S revolves around a step-sequencer)
Plankton: ANTS!
Soundmachines: Modulor114
Dreadbox: Erebus, Nyx
Kilpatrick: Phenol (rather Serge-like...a great intro to banana-patch methods)
Pittsburgh: Lifeforms SV-1 Blackbox, Microvolt 3900
...and I'm sure the list goes on. But anyway, by learning how these work in their normalized states (where applicable), it's easy to see how modules within those work, and how the patching process changes things around. And in most cases, these can be interconnected directly to modular systems, with the Korg and Moog devices being the only ones that have certain control signal tweaks that're necessary to make that work 100%. As for controllers (should you need them), my vote goes to Arturia and their Keystep and BeatStep Pro. Both are sequencers, the former also functioning as a keyboard controller and the latter being more pad-based.