Strangely enough, I can point you to a source. I've been reading the autobiography of Victor Fischer, a signer of the Alaska Constitution and a man who lived in Nazi Germany, the Soviet Union and the United States before age 16. It's called To Russia with Love: An Alaskan's Journey, and the first eight chapters might be of interest to you. His mother's book, My Lives in Russia, may also be of interest.

Now, Fischer was the son of American journalist Louis Fischer and a Soviet woman he met at the dawn of the Soviet Union. Victor was born in Berlin on May 5, 1924, moved to the Ukraine at age 3, moved to Moscow, back to Germany, then to Moscow again in 1933. He lived in Moscow from 1933 to 1939, leaving before the outbreak of WWII.

One of his best friends in Moscow was the (later) German film director Konrad Wolf, whom he met at the Liebknecht school, which geared its classes (all in German) to students who were primarily communist refugees fleeing Nazi Germany. The pair were friends with Lothar Wloch and did almost everything together. They nicknamed themselves "The Troika," got in trouble together, skipped school together, and Wolf later (unsuccessfully) tried to create a film about these years, which Fischer calls some of the best in his life.

"The older boys were achievers. They strived for political positions in the communist youth organization, the Komsomol, of which most aspiring activists were members. George hoped to one day be a high government official like those who held our father's attention." -- To Russia with Love: An Alaskan's Journey (p. 36).

Moscow was much smaller then and still had vestiges as a center of rural life, with horse-drawn carts clattering down the cobbled streets. But during our teenage years the Soviets transformed Moscow, to our fascination. We watched the subway being constructed and explored the underground vaults to hear our voices echo. The piles of sand excavated from the tunnels became our playgrounds. Occasionally, we would take shovels and help the workers, as much of their effort involved manual labor. -- To Russia with Love: An Alaskan's Journey (p. 37).

Fischer and his friends picked berries at the edge of the city, crawled through construction sites, and did normal kid things. "We had a fabulous time," he writes of summers spent outside the city.

Fischer was lucky: He was one of the privledged. His family enjoyed an apartment assigned by the foreign ministry. They shared a building with other foreign journalists. They had access to good food and high-ranking guests who were eager to be interviewed by Louis Fischer, who was extremely sympathetic to the Soviet Union.

Our excitement for the glory was real. We believed in the Soviet Union. The evidence of its superiority was all around us: In the new buildings and prosperity, in the education system, and in the equality enjoyed by all. All this contrasted to the stories we heard of the Depression in the United States, where the parks were full of the homeless, unemployed workers and where blacks could be lynched. ... This was the happy life of our group when the dark cloud of Stalin's terror descended. -- To Russia with Love: An Alaskan's Journey (p. 41).

He writes that this idyll broke in summer 1937 when they ran across a newspaper article. "Koni, Lothar, and I were riding on a trolley and reading Izvestia, the government newspaper, looking for football scores and international news. I found an article reporting that Marshal Mikhail Tukhachevsky had been charged with treason and demanding that he be executed. The next day, or maybe that same day, he was shot." -- To Russia with Love: An Alaskan's Journey (p. 43).

To them, this was a huge blow. Imagine Eisenhower being arrested and shot in 1951. It's that kind of big.

"We three boys had already seen the beginnings of Stalin's purge at work in newspaper headlines and radio news reports and in our own experiences at school, among our teachers. But at first this political stuff did not affect us directly; it did not strike close to home." -- To Russia with Love: An Alaskan's Journey (p. 44).

From kindergarten onward, teachers drilled all students with the party line: worship Lenin, revile Trotsky, then worship Stalin. At the beginning of each schoolday, each class recited, "Thank you, Comrade Stalin, for our happy childhood."

People were already used to occasional arrests and disappearances. Those had begun in the 1920s and continued through the 1930s as collectivization took its toll and millions of people were displaced during industrialization campaigns.

But by 1935, those seemed to be over. In December 1935, one of Stalin's lieutenants denounced the ban on Christmas trees in a letter published by Pravda. This was a de facto ruling that Christmas trees (called New Year's fir trees) were OK to enjoy again. Stalin himself said in a November 1935 radio message, "Life has become better, life has become more joyous."

Still, in 1936, the first stirrings of trouble were around. There was the Zinoviev trial, and even politically unastute kids noticed that. About the same time, the Soviet Union's position on Germans started to change.

"The German school we attended lost teachers to the purge. I remember people disappearing from school and students talking about it. But Lothar, Koni, and I didn't focus on that as a major event in our lives. We were more concerned, like the rest of Moscow, with the events happening in Spain." -- To Russia with Love: An Alaskan's Journey (p. 51).