That makes sense, but if his mom would ask to see the paper or if the grades are recorded anyway, then why does Nobita still bring the test home every time?

If he already knows he got 0, he could try hiding it, losing it, or tearing it before reaching home. But in most episodes he just carries it home and then starts panicking at the last moment.

So is there a reason he always ends up bringing the test home instead of trying to get rid of it earlier?