The tutorial found on Valence and crystal structure

You say that the hybridization for tetrahedral is \(s^2p^2\)

This is incorrect the hybridization is \(sp^3\)

Additionally, the following image is incorrect:

Though it does get the final hybridization right, it is missing the \(P_z\) orbital and the s orbital is incorrect. There is no dimensionallity to s. It is always a sphere centered at the origin.

For example the image below shows the 1s and 2s orbitals:

A more proper hybridization image (albeit it leaves out the antibonding orbirals but those are not really relevant here):

 

I believe you are correct so far as you go into the bonding orbitals of atoms. Frankly, I was surprised to see the s orbitals shown that way. My guess is that it resulted from a typo. Sz was probably intended to be pz, and the s just got lost. John

 

Hmm, guess they don't care.