Cheating in introductory programming classes (CS1) is a well-known problem. Various methods have been suggested to reduce cheating, but many are time-consuming, resource intensive, or don't scale to large classes. We introduced a class intervention having 6 low-effort commonly-suggested methods to reduce cheating: (1) Discussing academic integrity for 20-30 minutes, several weeks into the term, (2) Requiring an integrity quiz with explicit do's and don'ts, (3) Allowing students to retract program submissions, (4) Reminding students mid-term about integrity and consequences of getting caught, (5) Showing instructor tools in class (including a similarity checker, statistics on time spent, and access to a student's full coding history), (6) Normalizing help and pointing students to help resources. Via manual evaluation of similarity checker results on 7 held-constant labs with one instructor teaching 100-student sections, for two pre-intervention and two intervention sections, suspected-cheating reduced 62% (30.5% down to 11.5%). Because manual evaluation could be biased and is time consuming, we developed two automated coding-behavior metrics per lab - time spent programming, and % of students with highly-similar code - that may suggest how much cheating is happening. Time spent increased by 56% (7 min to 10.9 min), and % of students with highly-similar code dropped 48% (38.5% to 20%). We later repeated the intervention with a second instructor and different labs and achieved similar (in fact, even stronger) results, with time rising 84% (13 min to 24 minutes) and % dropping 66% (55.5% to 19%). All findings were statistically significant with p < 0.0001.
