I have to agree with "lmm" and "the_af" here. You can use Scala as a "Java without semicolons", and indeed that's what I recommend to those who want to learn Scala coming form an OO background. There is absolutely no need to use fancy Scala features like higher-kinds or monadic effects. Indeed, there is no need even to use functional features. Scala is a perfectly fine OO language. The one thing I recommend to learn once a learner gets a grip on Scala syntax is pattern matching matching and case classes. It's really easy to understand. And once you understand it, you never want to go back.
I have had a substantial number of undergraduate students learn Scala this way for their final year project and they all got it pretty quickly.