Disputes over the languages allowed in education resulted in friction between nationalities, but the education itself could lead to assimilation. For example, if Hungary increases its funding for its system of public education, but also forbids instruction in languages other than Magyar, this should lead to an increasing number of students assimilated into Magyar culture through their education but also increased irritation from members of nationalities that want instruction in their own languages.
It could perhaps be tied to your minority policy. E.g if you have full citizenship then your minority pops would increase in literacy at the same rate as your main culture pops with no gain in nationalism and be more likely to assimilate, but for each step down the policy ladder they would gain less literacy and more nationalism.