There are a very few southern states where LVNs can practice without an RN or MD supervisor, but Texas is not one of them.
Your education supervisors who are not licensed nurses may very well not know the scope of practice for LVN and RNs and may also believe incorrectly that it does not apply to school setting. Supervising nurses and other licensed professionals is not included in most education administrators' coursework.
In fact the Texas Board of Nursing states: "This is often a difficult concept for non-nurses to grasp as they typically do not understand that there are limits as to how far a nurse may expand his/her scope within the same level of licensure. Additionally, non-nurses often fail to realize that a nurse always has a higher duty to his/her patient. Regardless of facility policies or physician orders, the nurse has a duty to maintain a safe environment for the client and others. Because of this duty, the Board holds each nurse accountable to accept only those assignments that are within the nurse's education, experience, and knowledge, as well as the nurse's physical and emotional abilities."
LVNs in Texas: " NPA §301.353 and Rule 217.11(2) require the LVN to function "under supervision" of specific licensed practitioners, this precludes the LVN from functioning in a completely independent (without supervision) manner. However, direct (onsite or on-unit) supervision is not required. The LVN must have a resource person accessible at least telephonically or by some other similar means. Proximity to the LVN's practice setting and the level of licensure of a supervisor (RN, MD, etc.) must be determined by the LVN and his/her supervisor on a case-by-case basis and in accordance with any other laws that are applicable in the practice setting."
LVN Scope of Practice: http://www.bne.state.tx.us/practice/lvn-guide.html
There is a table as to what the LVN can do and what the RN can do.
Co signing LVN's notes by an RN: http://www.bne.state.tx.us/practice/faq-cosignlvn.html
They have a phone number and email address listed on the scope of practice link if you have any questions: email@example.com
or the Practice line at (512) 305-6802.