What are hops and how are they used in beer production?
Hops are flowers from a plant that contribute to the bitter and unique tastes of beer, but also to maintain freshness after beer fermentation. The flowers contain an oil called alpha acid resin, which isomerizes into its bitter tasting form when the beer is boiled. The longer the boil, a higher percentage of the alpha acid resin isomerizes, and the more bitter the beer tastes. Each variety of hops has its own characteristic mixture of alpha acid resin and other oils and are categorized into two types. Bittering hops have a high percentage of alpha acid resin and are added to the start of boiling in beer production, whereas aroma or finishing hops are added at different points towards the end of the boil and create a characteristic balance of taste and aroma.
How do scantrons work and why do we need to use a #2 pencil and not a pen or other writing utensil?
The original optimal answer recognition machine and sheet, which were invented in 1972 by the Scantron Corporation, operate by shining a light through the answer sheet and detecting which filled oval blocks the most light. Graphite from #2 pencils is the least transparent and must be used to minimize detection errors. However, scantron machines have progressed since then and now operate by algorithms that instead detect reflections on the sheet for the darkest marked oval. These machines accept pens and #2 pencils are no longer necessary, however darker or blacker marks are still best. Both types of scantron machines are still sold, so continue to use #2 pencils on your exams next week.