<p>Ages ago when I attended RPI, that’s exactly what we had for many tests, though we often didn’t turn our sheets in. Just creating the sheet was often good practice to learn the material - and it simulated to some degree the ability to look up a less-used formula. In the real world, you would do just that - look up the formula, rather than relying completely on memory, unless it’s something you use on a day-to-day basis. If you organized your sheet well, it was far easier than trying to look something up in the book, but it was only useful if the relevant information had been transferred to the sheet.</p>
<p>Of course it could be taken to the next step as well - turn the sheet in either as a separate grade, or as possible extra credit, allowing another way for the professor to know what student understand, and whether review is in order, if the misunderstood material is foundational to the rest of the class.</p>