For decades, schools installed hardwood floors or painted concrete. Both have fatal flaws. Hardwood warps from moisture and gets scratched by chair legs; concrete causes stress fractures in young athletes' joints.
Teach block starts on the poly surface. The 6mm thickness allows starting blocks to grip without tearing the surface (a common problem with cheap 3mm mats). For hurdle drills, the forgiving nature reduces fear of falling. classroom 6x poly track