score:12
Yes, until, more or less, mid 1950-ies (of course, the physical presence of Stalin in the room was irrelevant). It was not a "required code of behavior" (cf. grace after meal) and varied in time/space/status of the place (e.g., more likely in late 1930-ies, elite childcare in Moscow, less likely in late 1940-ies poor school in Siberia). However, if an adult (e.g., teacher or party functionary) prompted it, the refusal to comply would definitely have disastrous effects for the child and his/her family.
The phrase "спасибо товарищу Сталину за наше счастливое детство" (thanks to comrade Stalin for our happy childhood) was a meme that even I knew as I grew up in 1970-ies. It was not said in earnest then, but more as a historical reference.
Upvote:2
Yes.
Stalin was not just the maximum leader, he was also projected as a father figure, the great provider, etc. This theme permeated schools, orphanages, etc., where children were educated.
The most common phrase was "Thank Comrade Stalin for our happy childhood," but at mealtimes, "food" was operative word. The praise to an absent Stalin was similar to what religious people might say to "our Father in Heaven..." and at mealtimes, they would say "grace."