The assessment using Kahoot is a measuring tool to assess the extent to which the learning process is conveyed to students. Based on the interview result with teachers during the COVID-19 pandemic, teachers still use conventional methods in paper tests (paper). Therefore, an assessment instrument is needed that makes it more accessible for teachers to assess students during the COVID-19 pandemic. With the development of technology in education, the researcher develops instruments using Kahoot on the theme 6-subtheme 1 about temperature and heat for the fifth grade of elementary school. This development research aims to produce products in the form of instrument, suitability, and practicality of assessment instrument using Kahoot on theme 6-subtheme 1 about temperature and heat for the fifth grade of elementary school, to know assessment instrument using Kahoot and practicality. This was development research (R&D) with a 4D model consisting of the Define, Design, Develop, and Disseminate stages. The developed assessment instrument was tested to 6 students for the limited test and 13 students for the comprehensive test in the fifth grade of SD N Long. Techniques of collecting data were interviews, student response questionnaires, and documentation. While the data research instruments used were material expert validation sheets, media expert validation sheets, expert validation sheets, practitioners, and student response questionnaires. The results are in an assessment instrument using Kahoot on theme 6-subtheme 1 about temperature and heat. The validation results on aspects of presentation, feasibility, language, application and graphics get an average of 3.52 with a percentage of 84.12%, including the appropriate category. Student responses to the assessment using Kahoot in the limited trial get a proportion of 73.3% with practical criteria, and in the broad trial, it gets 85.6% with efficient criteria. Therefore, the assessment instrument using Kahoot on theme 6-subtheme one about temperature and is feasible and practical to use in assessments in elementary schools.