A great deal has long been known about student difficulties connecting real-world experiences with what they are learning in their physics classes, making learning basic ideas of classical physics challenging. Understanding these difficulties has led to the development of many instructional approaches that have been shown to help students make connections to the real world, think constructively, and learn the material successfully. However, what happens when making connections to the real world is more complicated. It is one thing to try to figure out how pushing a block with a constant force leads to constant speed, but it is very different to try to build toward an understanding of time dilation. Do the same instructional approaches work here? Also, is it possible that improved instructional approaches lead to improved student approaches when trying to make sense of difficult and very unfamiliar material? In this paper we describe a unique opportunity to perform a controlled experiment by interviewing identical twin brothers working together to resolve the twin paradox. These were intelligent and articulate science students with similar backgrounds but with diverging undergraduate experiences. One happened to take traditional physics classes and the other happened to take classes designed through Physics Education Research.