Elementary school teachers need to master the 21st century skills needed in teaching, namelycritical thinking, creative, collaboration and communication skills. For this effort the author needsto provide knowledge on how teachers can recognize and apply 21st century skills to be used intheir teaching in the classroom. One of them is by providing training on computer thinking skills(computational thinking) to elementary school teachers in the Kapau area, Tilatang KamangDistrict, Agam Regency by making programming using the Scrath application to be used to createlearning media. The training carried out received a fairly good response from the teachers whoattended and they stated that the application used was very suitable for teaching and used byelementary school children and very interested in being able to later apply it to their students inclassroom learning.

This study aims to produce a mathematics learning module based on a scientific approach in  grade  IV  SD  Negeri  38  Kuranji  that  meets  the  criteria  of  being   valid,   practical, and effective. This type of research is the researchs and development. The research model of development used is the 4-D model of development which define, design, develop, and disseminate. This research was conducted in the even semester of the 2019/2020 school year. Research instruments include validation sheets, practicality sheets (teacher and student response questionnaires) and effectiveness sheets (pre-test and post- test questions). In the validation process, the module is validated by 1 material expert, 1 design expert and 1 linguist. In the practicality process, the module was tried out by 1 teacher and 23 students. Based on this research, development scientifically based approach to learning mathematics in fourth grade produced modules that meet the criteria for very valid with a percentage of 90.29% votes, meet practical criteria with a percentage of 85.66% and meet the criteria of high effectiveness with percentages of 0, 71. So, it can be concluded that the Mathematics learning module based on the scientific approach in grade IV SD is valid, practical and effective as a resource in learning Mathematics in grade IV SD (Elementary School).

A reason for students’ low learning outcomes in Basic Mathematics 1 in PGSD FKIP Univer sitas Bung Hatta is found to be errors in answering the questions. This study aims to describe the errors and find factors that cause students errorly answer the questions in Basic Mathematics 1. This is a descriptive research using case study design with interview and test as data collection techniques. Errors analysis conducted with Newman Procedures shows that 4.89% of students experience Reading error, 8.22 % of students experience Comprehension Error, 12.67% experience Transformation Error, 15.11% of students experience Process Skill Error, and 1.56% of students experience Encoding Error. Factors that cause errors include abhorrance of math, carelessness in solving problems, reluctance to ask questions during lecture, and the absence of motivation to learn.

The aim of learning mathematics in universities is to improve students' mathematical abilities. One of the important mathematical abilities of students is understanding the concept. With an understanding of the concept, students will easily solve mathematical problems. This research is an experimental research design with One Group Pretest-Posttest Design. In the design of this study, researchers used one class as the subject of research. Before being given treatment, the pretest is first performed, then given treatment within a certain period, then given a posttest. The results showed that there was an increase in students' understanding of the concept after being given the application of the expository method.

This research aims to produce a effective module of area and perimeter plane  in primary school. This research is a research development by using the 4D model (define, design, develop, and desseminate). Phase desseminate not do. This research was to determine whether the module was designed has effective. Effectiveness module is obtained from data on student learning outcomes. The results showed that the modules of area and perimeter plane has a high effectiveness. Therefore, it was concluded that the module area and perimeter plane in primary schools has been effective.Keywords: module, area and perimeter, effective, primary school