What one in-game day is worth
A school day is split into as many as six segments, but only two of them are yours to spend: after school and evening. On days off it is daytime and evening. The real currency of the game is therefore two actions a day, not six. Some things cost no slot at all and are therefore pure profit: answering the teacher's question correctly in class, answering a classmate's question, bug catching, and planting or harvesting in the garden.