Integrated teaching is an inevitable trend in modern teaching that has been applied in Vietnam in recent years. Integrated teaching will contribute to developing special capacity, especially problem-solving capacity for students. The article presents some theoretical issues on integrated teaching. On that basis, the author proposes a process of designing integrated teaching activities for grade 1 mathematics, contributing to improving the quality of teaching mathematics in primary schools.Integrated teaching is an inevitable trend in modern teaching that has been applied in Vietnam in recent years. Integrated teaching will contribute to developing special capacity, especially problem-solving capacity for students. The article presents some theoretical issues on integrated teaching. On that basis, the author proposes a process of designing integrated teaching activities for grade 1 mathematics, contributing to improving the quality of teaching mathematics in primary schools.