I do not know and am having trouble finding out.

There's no such thing as a "Teaching Visa".

Presumably you mean a non-immigrant B visa, which you would get from a consular office, often in or near the embassy and maybe in other cities. 

You can apply for a non-b visa at if you have a visa exempt or tourist visa entry.

See:  https://www.immigration.go.th/wp-content/uploads/2022/02/2.FOR-WORKING-AS-TEACHER-NON-B.pdf

If you're going to Laos you may as well apply for your non-B there, as the requirements for converting in-country are far more draconian than they are for applying outside of the country.

 

(correction)

1 minute ago, JayClay said:

If you're going to Laos you may as well apply for your non-O there, as the requirements for converting in-country are far more draconian than they are for applying outside of the country.

He would be applying for a non-b visa based upon working as teaching not a non-o visa.

22 minutes ago, ubonjoe said:

He would be applying for a non-b visa based upon working as teaching not a non-o visa.

Quite correct. I don't know why I said Non-O as I have no experience with them.

 

If he's going to Laos you may as well apply for his non-B there, as the requirements for converting in-country are far more draconian than they are for applying outside of the country