Identifying in $\mathbb{S}^{n-1} \times [0,1]$ the set $\mathbb{S}^{n-1} \times \{ 0\}$ to a point and the set $\mathbb{S}^{n-1} \times \{ 1\}$ with another point. The result is homeomorphic to $\mathbb{S}^{n}$.
I don't know how to start because I don't know the result of the identification