## 3 Method
### Procedure for Measurement and Data Collection  
We considered the measurement of the additional time that students with different capabilities require to interact with computers to be particularly important for computer engineering and telecommunications students since computers are involved in most of their teaching activities, both at a theoretical level through the use of the virtual learning platform and at a practical level through the development of computer programs, computer networks, simulators, etc.  
We investigated the usability of the Moodle learning platform in the literature, and we found a satisfactory usability referring to factors such as efficiency, memorability, ease of use, and satisfaction [50]. [PERSON] et al. [51] described the good characteristics of the Moodle platform as well its functionality as expressed by students and teachers while they also reported barriers such as a lack of time spent preparing resources and using the platform and the fact that few students used the resources offered by the platform. In our case, a blind computing engineer, a specialist in accessibility, usability, and online learning, conducted an expert review of the usability of our Moodle platform to confirm accessibility. The expert followed some of the methods described by [52] such as heuristic evaluation, cognitive walkthroughs, and feature or standard inspection, corroborating the good results. Two tutors, also specialized in accessibility, guided the courses using debate fora, video conferencing, and e-mail as communication mechanisms.  
The students completed a first questionnaire referring to their personal information prior to the effective start of the course. We measured the time that students took to answer this first questionnaire. We calculated the statistical results by comparing the times used by the three groups of students with different capabilities with that used by the control group (students without any limiting condition). Working with two different types of courses with several editions also contributed to greater soundness in conclusions.  
Before starting the courses, students were informed of our research work and our goal of improving e-learning design for people with different capabilities. However, we did not disclose the relevance of the initial questionnaire for time measurement, avoiding a Hawthorme-like effect. All students participated in the study by taking the initial test before starting the course.  
Time taken by students when answering the initial questionnaire was calculated by the Moodle platform using the time at which they began to answer the questionnaire and the time at which they completed it. Students did not have a time limit for the task. This may represent a risk as some students had breaks when answering the questionnaire. However, after reviewing duration data, we discarded clear outliers. Furthermore, data for blind students were aligned with times for blind people shown in ref. [15], measured with a very precise manual time measurement method. This indicated confidence in the data and the reliability of the sample.  
After conversing with those students, we assigned them an amount of extra time informally determined as the results of our research were not yet available to use as a guideline. The final satisfaction questionnaire at the end of the course showed positive results: we could not infer that students were demotivated or unsatisfied with the course, so we considered recorded times as representative of normal interaction of students during an online course.  
The two main differences between our approach and the contributions of precedent methods in the literature are (a) the measurement of time through the system, avoiding manual methods that would add human errors, and (b) the use of a questionnaire on students' personal profiles to avoid a possible bias due to the need for previous knowledge. Our approach also added a group of students with reduced motor capacity and this represents an additional contribution in comparison to previous works.