The teacher is lawful authority
The bishop and the priest he delegates the parish to are the lawful authorities. As far as I am aware, no catechist or lay teacher is a
lawful authority. You’ll have to provide some evidence to show otherwise.
I feel it is wrong to tell a child to disobey a teacher. If it is a serious matter, I would remove my child from the program and work to have the teacher removed. I would obey in something not a matter of faith or morals.
Yet according to
Redemptionis Sacramentum, this
is a serious (grave) matter (my emphasis and comments):
"Although the gravity of a matter is to be judged in accordance with the common teaching of the Church and the norms established by her,
objectively to be considered among grave matters is anything that puts at risk the validity and dignity of the Most Holy Eucharist: namely, anything that contravenes what is set out above in nn. 48-52, 56, 76-77, 79,
91-92 [quoted by myself in http://forums.catholic-questions.org/showpost.php?p=5042042&postcount=2”]
post #2 of this thread], 94, 96, 101-102, 104, 106, 109, 111, 115, 117, 126, 131-133, 138, 153 and 168.Moreover, attention should be given to the other prescriptions of the Code of Canon Law, and especially what is laid down by canons 1364, 1369, 1373, 1376, 1380, 1384, 1385, 1386, and 1398.
"Furthermore, those actions that are brought about which are contrary to the other matters treated elsewhere in this Instruction or in the norms established by law are **not to be considered of little account, but are to be numbered among the other abuses to be carefully avoided and corrected. [So even if it is not grave matter, it is still to be corrected, not to be treated lightly, glossed over or ignored, and to be “carefully avoided”; if a catechist teaches contrary to the norms of law, they are to be ignored/disobeyed and corrected. The important thing here is not fidelity to an individual person, but to the Church.]
**
“The things set forth in this Instruction obviously do not encompass all the violations against the Church and its discipline that are defined in the canons, in the liturgical laws and in other norms of the Church for the sake of the teaching of the Magisterium or sound tradition.
Where something wrong has been committed, it is to be corrected according to the norm of law. [And R.S. makes it quite clear that this is everyone’s responsibility; cf. 183]”(Redemptionis Sacramentum 173-175)
Whether it is to do with faith and morals is not really the issue here. The issue is whether what the catechist teaches (in this instance) is against the norms of law. It is–ergo, they are to be corrected, and not to be obeyed. (Even if they were a *lawful *authority, if they taught contrary to the norms of law, they would have to be corrected. Bishops, after all, are still human, and make mistakes just like the rest of us!)