One of the factors that determine the success of mathematics learning is the learning media used. Learning media can help students to create mathematical abstract mathematics that is abstract. In addition to media, meaningful learning is a learning that is adapted to the students' cognitive development. According to Piaget, junior high school students are at the formal stage of thinking, but the reality in the field has not been entirely capable of formal thinking so that a learning media is needed that is able to serve students with different cognitive development. By using the principles of ASSURE and VISUALS, it is necessary to develop a medium tailored to the cognitive development of junior high school students. Semi-concrete media development can be used as an alternative to mathematics learning. Some concrete semi that can be used in learning such as number cards, number lines, and comics.