Is there any basis in religion for not accepting the testimony of elementary school teachers in court, as is common among the general public?

Merely teaching children is not considered a disqualifier for testimony. Scholars have mentioned seven conditions for witnesses: Islam, sanity, puberty, freedom, attentiveness, uprightness (adalah), and lack of accusation. They did not include not practicing the teaching of children among these. Uprightness (adalah) is forfeited by engaging in permissible acts that undermine decorum (murū’ah), such as walking barefoot or eating in the streets, if these are considered breaches of decorum in a specific environment. As for teaching children, it does not invalidate uprightness (adalah) because it is a communal obligation (fard kifayah), unless another condition for testimony is compromised.