The purpose of this paper is to describe an experimental study we ran in 2010 in Uruguay to identify effective learning object formats and adequate conditions for using multimedia contents with kids in “real world” learning contexts. Uruguay is part of the OLPC (One Laptop Per Child) initiative that aims to distribute low cost laptop PCs (called XOs) in developing countries schools to foster kids' learning according to the instructional principles of constructionism, learning-by-doing and social constructivism theories. This country is the only one that reached the "saturation" goal, covering the entire primary school population (teachers included). For this reason the capital Montevideo was an appropriate “en plein air” research field because most of the students haven’t evident impairments using educational technologies and digital learning contents. In order to find out how to reduce cognitive load and increase learning performances using infographics, animations and interactivity, we arranged an experimental study that involved 360 early adolescents from 16 classes of critical context schools in Montevideo. We identified a scientific topic, the food chain process, and presented it in 4 different ways. We modified supports and instructional formats according to Mayer’s ‘Multimedia Learning Principles’ and the ‘First Principles of Instruction’ theory by Merrill. The first part of the research focused on Self-Directed Learning in real contexts and investigated the use of different instructional strategies (e.g. topic-centered vs. task-centered; linear vs game-based) handling the learner’s User Experience in order to increase the engagement for the proposed formats. Considering the target of early adolescents, we introduced a likeable virtual tutor to manage explanations, feedbacks, and focus on relevant information. We used infographic techniques to combine analytical and synthetic schemas and to enhance the aesthetic perception. The second part of the study aimed to identify the best use of multimedia contents in classrooms comparing 3 learning settings: Self-Directed Learning, Cooperative Learning and Teacher-Directed Learning. In order to measure the impact of content design format and learning setting we identified 5 instructional objectives using a Content/Performance Matrix, and evaluated the outcomes by 4 kinds of tests: Retention, Comprehension, Problem Solving Transfer, Delayed Problem Solving Transfer (after one week). We also used a qualitative tool: a self-administered questionnaire for the User Experience satisfaction, to discover relationships between students performances and individual preferences matched with satisfactory learning experiences.