The principal parts of verbs may arguably be learnt early. The relation of so many Latin verbs to English – especially the supine of them – can enthuse the likely lad or lass with philological inclinations (something that the Cambridge Latin Course almost fails to do) and presents to all pupils a realisation about their own language.
Principal parts are not foreign to English, and the continental child who is being taught English thoroughly will learn a list of those verbs that form in the ‘strong’ mode, i.e. as in German: forget, forgot, forgotten; lie, lay, lain; swim, swam, swum. For a list of these that can be used for practice, see the Morphology page: one or two of them are challenging.
After noticing this, the idea of Latin principal parts becomes more intelligible, once it is explained that Latin has four instead of three. (For that rare child who is keen on such things, and is already thinking of Greek, it can be mentioned in passing that a Greek verb can have seven.)
The supine, which roughly corresponds to the English PPP, is of interest, not only for the hundreds of English words ending –ion, but for the further possibilities. Most Latin verbs do not produce a full set, but the common verb audio does: audition, auditor and auditorium.
Latin words like lavatorium and laboratorium are of interest, as are purgatorium, conservatorium and dormitorium; victor, narrator, tractor, motor, doctor, navigator, creator, inspector, actor etc.
By the way, the word factorium was used only to mean an oil-press. Not many things in the ancient world took place on a large scale, but that did.
Later, the derivatives of the present participle are of interest to many children: regent, agent, tangent (and contingent), cogent, patent, latent, fluent, etc.
One child, who later became a well-known classicist and author, said he decided what was the subject for him the moment he saw some of these things written on the board in his classroom.
Next post: Mnemosyne and the wiring of the brain.