http://www.upenn.edu/pennnews/current/2011-11-17/features/bus-minus-whale-equ... The schools in this article are using Mathematics in Context, a middle school curriculum cooperatively developed by math educators at the University of Wisconsin and the Freudenthal Institute, the Netherlands. The philosophy behind the curriculum is called "Realistic Mathematics Education" (RME), and contexts are a key feature. However, realistic doesn't necessarily mean real-world; a better translation from the original Dutch would be "imaginable." If the curriculum is being modified because kids can more easily imagine buses than whales, then it seems like it would still be in the best spirit of RME.