When selecting height-adjustable school furniture, prioritize ergonomic design that supports the natural curve of the spine. The adjustment mechanism should be user-friendly, typically using a manual bolt-fix system or a crank handle for durability. Ensure the desk surface features a non-glare matte finish to reduce eye strain and that the chair has ventilation holes for comfort during long study sessions. Material-wise, look for high-density polyethylene (HDPE) or ABS plastic for seats, and cold-rolled steel tubing with a thickness of at least 1.2mm to 1.5mm for the frame to ensure structural stability.