Short answer. Yes, and the duty is stronger than the Labor Code article suggests. That article was repealed by Republic Act No. 10361 (2013), the Batas Kasambahay, which governs domestic employment and provides for a working minor's access to education, alongside the child labour rules under Republic Act No. 9231.
What the law says
If the househelper is under the age of eighteen (18) years, the employer shall give him or her an opportunity for at least elementary education.
Labor Code, Article 146 — Opportunity For Education. Read the full provision →
The old article and its repeal
Article 146 of the Labor Code said that If the househelper is under the age of eighteen (18) years, the employer shall give him or her an opportunity for at least elementary education. It added that the cost of that education formed part of the worker's compensation unless the parties stipulated otherwise. The article was expressly repealed by Republic Act No. 10361 (2013), the Batas Kasambahay, whose repealing clause struck out the whole Labor Code chapter on the employment of househelpers. Do not take the standard from those words. In particular, the clause allowing schooling to be charged against her pay should not be treated as live.
What the current framework requires
Two statutes matter here. Republic Act No. 10361 governs the employment of domestic workers and provides for the access to education and training of a kasambahay who is still a minor, along with the working conditions and benefits the Act guarantees. Separately, Republic Act No. 9231 (2003), amending Republic Act No. 7610, governs child labour generally and requires that schooling continue, restricts what a young worker may be put to and caps working hours. Read both, because a minor kasambahay is a working child as well as a domestic worker, and the stricter requirement is the one that binds.
Age is the first question, not the second
Before asking about schooling, ask whether the child may lawfully be working in the household at all. Child labour law fixes a minimum age and narrows sharply the situations in which anyone below it may work, with a permit requirement and hour limits, and it bars anyone under eighteen from hazardous work. A household that engages a young teenager as a live-in helper on the assumption that the arrangement is charitable is still an employer, and is answerable under those rules. Willingness on the part of the child or her family does not change the analysis.
In practice
Schooling has to be real rather than nominal. That means work hours arranged around class, time to study, and no expectation that she will simply drop out when the household is busy. Keep the employment contract, the registration papers and a record of the hours actually worked, because hours are where this usually breaks down. If a minor is being kept from school to work in a household, that is a child labour matter and is enforced as one. This page gives general legal information rather than advice on a particular household.