A Simple Acid-Base Intro Lab

We're nearing the end of the year and this is when I do my simplified acid-base unit with first year chemistry students. We've just finished solutions and concentration, so this is a good extension unit where all of the same ideas are present (ions, concentrations, etc) in a specific context. It's also a good unit to probe students for previous learning because, at the surface, they all have a general idea of what acids are and I'm able to push into that knowledge to help them build a fuller chemical model. For this lab, we start with a card sort). I ask them to group up the properties however they'd like as a way to get them thinking about the macroscopic observable properties for acids and bases. Many of the cards are "either/or," so I don't do much questioning unless they have contradictory cards in the same pile. Once they have their categories, they set the cards aside and grab samples of eight common household solutions. I use 24-well microplates because it's simple cleanup and…