If your parents pay for you to go to school and you ditch, is that stealing?
I don't think it would considered pure stealing of money, though it might be.
Certainly, however, one who skips school when one's parents believe that they are attending is committing 'geneivas daas' by misleading their parents. This is derived from the prohibition of stealing found in the Torah (Leviticus 19:11).
How can it be stealing? Stealing requires that the thief walk away with something to which he is not entitled. All the kid gets here is free time. The cost to the parents is the same, so he can't be stealing their money.
He is, on the other hand, wasting their money. It seems analogous to taking the dinner he was served and throwing it out. It isn't theft because he was given the food freely, but he is not using it in the way it was intended. Arguably, a plate of food is a gift on the condition that it be eaten, in which case it could be theft, but this seems a slightly unusual understanding. I don't think parents think, "This is a gift on condition" when paying tuition or when making dinner.
I would be interested to know if their was any actual halachic literature on the subject but it seems to me the answer is pretty clearly no.
Parents pay for a service, that their children obtain an education, not for a continuous task to be preformed like an assembly line. In other words every moment in the classroom does not translate into a moment of education and this is understood by all involved. While a certain amount of time is generally required to reach the goal, achieving the goal is a process and it is possible to "catch up" after an absence.
This is not to deny that skipping cannot have negative consequences or that it is not inappropriate, but it seems to me that it is inappropriate for what it is, skipping, without needing to make it into something else.