Students' 21st-century skills are acquired through literacy. Teachers can train students to read, write, and solve problems using a mix of teaching strategies, and ePortfolios. However, in reality, the teaching carried out by teachers has not been able to develop students' 21st-century skills, due to the low literacy skills of teachers. This study aims to develop the 21st-century skills of elementary school students by improving literacy skills of reading, writing, speaking and problemsolving in Indonesian, Science, Social Sciences, and Citizenship Education subjects. This is done by providing technical guidance to elementary school teachers in designing constructivist lesson plans, worksheets, and reading literacy assessments. The findings suggest that the teacher follows all learning procedures in training students to acquire all 21st-century skills. The teacher develops students' creativity skills through project work that produces artifacts of students' work. The teacher develops students' collaboration/collaboration skills through small groups. The teacher trains critical thinking skills through literacy programs that support students to acquire many new words from new insights; The development of communication skills can be done by the teacher by preparing each student in turn to present their answers, ideas, and ideas. Problem-solving and inquiry skills in groups can be developed by organizing equality and involving all students.