American Journal of Educational Research, 2018, Vol. 6, No. 11, 1522-1530 Available online at http://pubs.sciepub.com/education/6/11/10 ©Science and Education Publishing DOI:10.12691/education-6-11-10 Development of Learning Devices through Knisley Mathematical Learning Model to Improve Mathematical Understanding and Disposition Ability of Class VII SMP Swasta Tamora 2 Siti Hanijah Br. Saragih 1 , Edi Syahputra 2 , Syafari 2 , Yuli Ragelia Sinaga 3,* 1 Education of Mathematics Post Graduation, Universitas Negeri Medan 2 Department of Mathematics Education, Universitas Negeri Medan 3 Department of Mathematics Education, Universitas Negeri Medan, Medan, Indonesia *Corresponding author: sitihanijahsaragih@gmail.com Received October 05, 2018 Revised November 10, 2018; Accepted November 21, 2018 Abstract This study aims to find out (1) validity of learning devices developed through the knisley mathematics learning model; (2) the effectiveness of learning devices developed through the knisley mathematics learning model; (3) the level of ability of students' mathematical understanding by using learning tools developed through the knisley mathematics learning model; (4) the level of students' mathematical disposition by using learning tools developed through the knisley mathematics learning model. Researchers develop learning tools in the form of teacher books, student books, student worksheets (LKS) and learning implementation plans (RPP). Validation of learning devices was carried out by 3 experts and two practitioners and obtained a total average value of validity at intervals of 4 ≤ Va < 5 with valid criteria. Mathematics learning devices developed through a technical mathematic model in improving the mathematical understanding and disposition skills of the developed SMP Swasta Tamora 2 students are effective. Based on the results of the ability of mathematical understanding of the test I and trial II, it was found that the average increase in students' mathematical comprehension ability was 4.12. Based on the results of the students 'mathematical disposition questionnaire in trial I and trial II it was obtained that there was an increase in students' mathematical disposition that is equal to 0.61. Keywords: understanding mathematical ability, 4-D model, learning devices development knisley mathematical learning model Cite This Article: Siti Hanijah Br. Saragih, Edi Syahputra, Syafari, and Yuli Ragelia Sinaga, “Development of Learning Devices through Knisley Mathematical Learning Model to Improve Mathematical Understanding and Disposition Ability of Class VII SMP Swasta Tamora 2.” American Journal of Educational Research, vol. 6, no. 11 (2018): 1522-1530. doi: 10.12691/education-6-11-10. 1. Introduction Learning consists of the process of learning and teaching which is an important core of education. According to Trianto [1] learning is a two-way interaction process between students and educators and between them there is intense and directed communication towards a predetermined target. Learning provides the widest space for students to explore information and knowledge, so learning must be prepared and carried out effectively by involving active students directly. The success of a teacher as a professional educator can be seen from his success in managing learning. Professional teachers will do thorough preparation before teaching. Suparno [2] suggests that: before the teacher teaches (the preparation stage) a teacher is expected to prepare the material to be taught, prepare teaching aids/practicum to be used, prepare questions and direction to lure active students to learn, learn the state of students, understand weaknesses and strengths of students, as well as learning the students' initial knowledge, all of which will be broken down in the learning tools. Learning tools facilitate students to actively develop their potential to become a competence. Therefore, the teacher has an obligation to provide a learning experience for students to carry out various activities that allow them to develop their potential to become the competencies established in a plan. According to Trianto "learning devices are devices used in the learning process". Furthermore, according to Suhadi [3] stated that "learning devices are a number of materials, tools, media, instructions and guidelines that will be used in the learning process." From these opinions it can be stated that the learning device is a set of tools or means used by teachers and students in the learning process in class. The set of tools includes the Learning Implementation Plan