Background:
The Mechanical Waves Conceptual Survey (MWCS), presented in 2009, is the most important test to date that has been designed to evaluate university students’ understanding of four main topics: propagation, superposition, reflection, and standing waves. In a literature review, we detected a significant need for a study that uses this test as an assessment tool and presents a complete analysis of students’ difficulties on the test. This article addresses this need.

Material and methods:
We administered the MWCS at a private university in Mexico to 541 students.

Results:
In this article, we present a complete description of these students’ performance on the test, a description of their main difficulties, an elaboration of these main difficulties in terms of students’ inappropriate conceptions and recommendations for instruction based on the results obtained by the test.

Conclusions:
Our analyses may be used by instructors and researchers who intend to use the MWCS or create new instructional material.