Lesson over 8.1: https://drive.google.com/file/d/1ZKhB6ykeER8SM3zHRLFsRkBNSARxhUMZ/view
Lesson over 8.2: https://drive.google.com/file/d/1jTrPdNqS10yxD3DAE-NQGLSbQ4_hsTla/view
Lesson over Volume: https://drive.google.com/file/d/1ZxZXUBaV6eIEk2wEBZajcQjD0kteawgy/view
Lesson over Surface area: https://drive.google.com/file/d/1ZIn_1dlVZBP-4xxeAZeNmJzl_f_Z-5-R/view