Acid--base chemistry is an important and challenging topic for virtually all chemistry students. Recent works have focused on conceptually linking molecular and symbolic representations to experimental evidence for many chemical concepts. In this work we describe a laboratory exercise designed to address students' conceptual challenges regarding acid--base chemistry, particularly with respect to organic acids, titrations, and pK[subscript a]'s. This work is part of a series of laboratory exercises developed for prehealth students using the MORE (model, observe, reflect, explain) pedagogy. In this lab, students titrated an amino acid with sodium hydroxide according to lab procedures typically used in a prehealth lab. Our work differs from traditional laboratories in the emphasis on connecting molecular-level representations to symbolic representations and experimentally derived evidence. Using this course environment, we sought to understand the ways in which students' understandings (molecular-level, symbolic, or evidential) are coconstructed or discrete. We further sought to guide students toward connecting these understandings and report on our successes and areas for improvement.