Here are some possibilities:
General terms:
* Omwana wa sikuli: This literally means "child of school" and can be used as a general term for a school boy.
* Mwalimu: This is the general term for a "student." However, the specific context will clarify whether they are a boy or girl.
More specific options:
* Omwanaume wa sikuli: This literally means "man of school" and emphasizes the male aspect.
* Mwanafunzi wa kiume: This means "male student."
* Omukoloni wa sikuli: This means "school boy" in the Luhya dialect spoken in Kakamega.
Note: The specific term used may also depend on the age of the school boy. For younger boys, "omwana wa sikuli" is more common, while for older boys, "omwanaume wa sikuli" or "mwanafunzi wa kiume" may be preferred.
It's always best to check with a native speaker to ensure the most appropriate term is used for your specific situation.