## 1 Introduction
There are studies that support the effectiveness of computer-based cognitive training programmes as intervention tools in preventing and delaying cognitive decline in old age [8]. A study on cognitive development in adulthood and old age [9] emphasises the importance of learning new subjects in older adults to improve their quality of life. Introducing computers to older people can have a positive impact on their cognitive functioning, mood, and social integration [10]. However, this group may face challenges when learning computer science concepts, particularly those with low educational levels [11]. Factors such as age, education level, income, and social isolation can significantly influence computer and Internet use among older people [12]. Techniques such as Computer Science Unplugged (CS Unplugged), in which computer science concepts are taught without the use of computers, can help to overcome some of the existing barriers to teaching computer science concepts to the older population [13]. In this context, the work carried out has a twofold objective, as follows:  
* To validate the suitability of using unplugged computing activities to teach computing concepts to an adult population, particularly older people. * To validate the adaptability of the L2T2L pedagogical strategy to transfer computing knowledge from university students to older adults. L2T2L (Learn to Teach to Learn) is a learning by teaching methodology that has students learn and then, in turn, teach that learning to other students, in a cascade starting from university [14]. Variants of L2T2L were previously used to transfer computing knowledge from university students to primary and secondary school students [14; 15] or from university students to prisoners [16]. The case study presented in this article was conducted in centres for the elderly in Lima, Peru, during the 2023-2024 academic year with 140 volunteers. Through CS Unplugged exercises based on games and recreational activities, students from the Universidad Cientifica del Sur, Peru, initiated the teaching of computer concepts to the elderly without the use of computers. This study has not only shown the positive attitude of the elderly towards computing, but also the suitability of the combination of CS Unplugged and L2T2L to transfer computing skills from the university to the centres for the elderly. Initiatives such as the one presented in this work can significantly contribute to an improvement in the cognitive activities of the elderly and to re-education, improving the quality of life of this population in the community. This article is structured as follows: Section 2 presents a review of the literature on teaching computing to older people, together with an introduction to CS Unplugged. Section 3 focuses on describing both the methodology used to transmit knowledge associated with certain topics of computing from the university to centres for the elderly and on detailing aspects related to its implementation. Section 4 elaborates on the results obtained. In Section 5, comparisons with the results of previous studies carried out with different populations of students and with inmates in prison are presented. Finally, Section 6 points out some conclusions and future lines of research.