So, in Algebra 1 we took an entire day in May and reviewed proportions (based on this beautiful nugget from Jonathon Claydon). We measured objects around the school that were too tall to be measured otherwise: walls, flagpoles, ceilings, etc. We did this by comparing our 'real height' with our 'fake height'. Think of any proportions problem from middle school and you're half-way there.
'Real world' without being trite AND it gets students out of their seats--I can't ask for much more than that in a single lesson.