This paper presents the development and evaluation of an in-class intervention based on persona cards, an accessibility kit created to introduce users with diverse needs to postsecondary students and motivate them to adopt accessibility guidelines. The cards created include 16 profiles of users with visual, hearing, motor, cognitive, and multiple impairments. To assess the effect of the intervention on the students' knowledge about accessibility, five in-class interventions with 134 students were conducted in the USA and in Spain. The intervention aimed at encouraging the discussion about how future designers can make interactive solutions more accessible for users with diverse needs. To assess the acceptability of the intervention materials among instructors, an online survey was utilized, and 30 respondents rated the usefulness, impact, ease of use, and their willingness to adopt the cards. They also provided suggestions to facilitate adoption. The statistical analysis of the results using Mann-Whitney tests indicates that the usage of personas during the intervention had a positive effect, improving the students' understanding about accessibility. Instructors who responded to the survey considered the persona cards to be easy to use, diverse, and useful. The intervention increased the students' interest and motivation to apply accessibility principles in their work practices and employ universal design in their lives. Also, instructors reported a positive acceptance regarding the adoption of the cards in their technology-related courses.