Do children under bar/bas mitzva get schar for doing mitzvos? (Regular mitzvos such as learning Torah, brochos, shabbos etc., as well as things such as doing a favor for a parent or sibling in order to get a mitzva etc.)
Thank you for your qustion.
Children most definitely get sechar for the mitzvos that they do. As an example, the gemora (Sanhedrin 110b says That a child merits a portion in Olam Haba from when he can answer Amen. Another gemora says that the world exists in the merit of small children’s torah learning. They defniitely get sechar in Olam haba for that. Thisis true even though the child doesn’t yet understand what he is saying. It is still a mitzva and he will get a reward for it. How uch more so when they do a itzva b ecause they know that it is a mitzva.