Not only was 'political education' - in the sense of civics, to relate to American politics - mandatory, 'political education' pertaining to Marxism, dialectical materialism, and the Revolution was much more ingrained in the culture. 'Political reliability' is an interesting phrase - this might mean 'faithfulness to the USSR' or 'dogmatic' but it almost certainly doesn't mean 'well, broadly educated on diverse political topics.' The successors to the communist intellectuals of the 1930s were oftentimes peasants or factory workers that had been integrated into the system throughout the late 1920s and 1930s.

Much of the scholarship on this question is from the Cold War, and should be regarded somewhat carefully. Many Western characterizations are incomplete and sometimes flat-out incorrect. I recommend Bereday and Stretch for an example of good Cold War scholarship on political education; Katz is worth taking a look at as well.

For the actual process of formal political education, "Constitution of the USSR" composed two hours per week for eleventh graders; 'economic geography' the same; history four hours, and literature three hours. Foreign language is included here at three hours, for a total of 14 hours per week of 'political education' (13). Understand literature to not really have an American comparison - Socialist Realism is the dominant literary tradition taught here, along with particular Imperial literature that presents a justly negative view of Tsarism, while foreign language is taught in a rather dissimilar way that encourages practical translation rather than spoken fluency.

A very interesting early Soviet field was pedology, the holistic study of children's development, that was banned by Stalin. This field attempted to place children's physical and intellectual progress in Marxist terms; this may be of interest to see just how ingrained politics were in the Soviet Union, and how citizens attempted to embrace this ideology. In 1938 Stalin writes a very bizarre reinterpretation of Marx called Dialectical and Historical Materialism that becomes central to political education in the late Stalin era. The state policy of diamat pervades everything from classrooms to science, and persists into Khrushchev's rule. In this sense 'political education' was everything Soviet students were taught (though we might consider American textbooks of the Cold War critically as well).

One of the things the Soviet Union was quite successful in was education, and it would be difficult to remain 'willfully ignorant' on politics. Other references to look into are Everyday Stalinism, Education and social mobility in the Soviet Union 1921-1934, and Education in the Soviet Union: Policies and Institutions Since Stalin, which is a good reference text on Khrushchev and Brezhnev era education.

Bereday, George and Bonnie B. Stretch. "Political Education in the U. S. A. and the U. S. S. R." Comparative Education Review 7, no. 1 (1963): 9-16.

Katz, Zev. "Party-Political Education in Soviet Russia 1918-1935." Soviet Studies 7, no. 3 (1956): 237-47.