TABLE 1.

Summary of laboratory course design from 2014–2016.

Design features	2014	2015	2016
Background and lab purpose	Background on E. coli strainsPurpose of lab is to “show that mutations can sometimes be beneficial”	Background on E. coli strainsPurpose of lab to investigate the question: Is it better to mutate a lot or a little (and under what conditions)?
Lab activities: experiment	Basic experimental procedure including plating on three types of media (LB agar, LB + lac, MacConkey) shows advantage to mutating in novel environments	Plating on LB agar and LB + rif only. Colonies on LB agar are countable allowing inferences about fitness in nonselective mediaCompetition experiment comparing strains plated on LB media supports multiple predictions and outcomes
Lab activities: computer simulation	None	Thirty-minute agent-based simulation activity to explore conditions under which virtual strains with different mutation rates have advantage	One-hour simulation activity allows students to run comparisons and plots to show mutation frequenciesGTAs emphasize “puzzling” output for whole class
Role of instructors	Pre-lab quizGTA lecture reviewing lab manualOptional discussion questions	Small-group and whole-class discussions about relative benefits of higher/lower rate of mutationSmall-group and whole-class discussions of patterns and possible interpretations
Assessment guidelines	Guidelines emphasize following directionsDiscussion section should include a statement of whether data conformed to the expected hypothesis	Guidelines emphasize students making sense of dataDiscussion section should discuss “ideas and evidence”Optional inclusion of output from simulation
Peer review	Draft and exchange methods in class	Peer review (introduction, methods, results only)	Peer review of discussions emphasizing looking for consistent reasoning