Update: March, 05/2021 - 09:11 | Lùng Thị Hoài (second, left) and her electric firework device in 2021 STEM festival in Si Ma Cai District, the northern mountainous province of Lào Cai. Photo khoahocphattrien.vn LÀO CAI Lùng Thị Hoài, a Nùng ethnic minority student of Nàn Sán Secondary School, uses equipment to show off electric fireworks she and her peers made to celebrate the 2021 STEM (science, technology, engineering and mathematics) festival in Si Ma Cai District, the northern mountainous province of Lào Cai. STEM is an approach to learning and development that integrates science, technology, engineering and mathematics.