Well, that's interesting, Rod, because in GB English words like 'picture' and 'feature' are commonly said with the 't' as a /ch/. 'Choob' sounds unusual to GB English ears because we don't say 't' as /ch/ at the beginning of words, but the Scots (who the poster was referring to) do.
I am always very wary of Phonics being used as 'elocution lessons' though I do encourage "Say it in a 'spelling voice" for words where pronunciation and spelling have diverged very dramatically.
Hi maizie,
Taking your last point first, why be "wary of Phonics being used as 'elocution lessons'"? Someone else made the point that we send kids to school to become educated. Certainly, learning to pronounce words in a more broadly accepted form should be part of any decent education. This is in no way meant to denigrate a local accent, but that's what they are, local. Once outside the local area, retaining a local accent will definitely serve many people poorly, especially if they attempt to get work in certain fields requiring a lot of verbal communication with customers or strangers.
As to words like "picture" and "feature," and I would add, "statue," I long ago decided in my curriculum to not treat these as pic-cher, fea-cher, and sta-chew. Ironically, it was a British contributor to a forum who convinced me. Instead, she maintained that both "ture" and "tue" should be thought offor both spelling, and for understanding their phonics structure, but not for speakingas having long-u sounds (which I indicate as /ue/, as in the word "cute".)
Since then I have always taught "statue" as sta-/t/ue/, and "stature" as sta-/t/ue/r/, and have explained to every child that the precise pronunciation of these two endings is a bit of a tongue twister, but that they should think of them in that manner for spelling purposes. This simplifies matters by gently forcing the pronunciation of those endings into already-taught code. Ditto for words like "fortune" (for-/t/ue/n/).
In fact, as I think it over, it's actually the /ue/ sound that complicates the pronunciation of "ture," "tue," and, I suppose, the British "tube." In the U.S., we've converted the long-u to an /oo/ sound in words like "tube" and "tune" and say "toob" and "toon" instead to avoid the tongue-twisting.
The /ue/ sound is a dipthong ending in the /oo/ sound, but the onset of that dipthong is difficult to pronounce after certain consonant sounds, like /t/ and also /d/, so /t/+/ue/ tends toward /ch/oo/, and /d/+/ue/ tends toward /j/oo/, just because of how the onset of the /ue/ sound pulls our jaw forward. At least that's how it feels to me.
Rod