EDUCATIONAL RESOURCES WITH PERCENTAGES FOR THE DEVELOPMENT OF THE VISUAL ESTIMATION.

Computer models of tasks related to percentage are presented. The files are created with the dynamic software GeoGebra and are provided in the Virtual Mathematics Laboratory, developed by the Institute of Mathematics and Informatics of the Bulgarian Academy of Sciences. The goal is to create conditions for the development of the visual estimation of a percentage, which also supports the understanding of the concept. The computer models contain rectangles and circles. Help and feedback are provided. Options for obtaining a new example and feedback are described. Emphasis is placed on the analogy of the tasks in the four presented topics, each of which contains four tasks. An assessment of the resources is presented, obtained from an anonymous survey with teachers from different subject areas and teaching at different educational levels. The assessment is based on the criteria of easy technical orientation, design, usefulness, entertainment, motivation to solve. The simultaneous development of digital and mathematical competence when working with these resources is commented on, as well as the possibility of their use in STEM centers. Ideas for expanding the resources for checking and developing the percentage calculator in several directions are described. [ABSTRACT FROM AUTHOR]