Bonjour Kristin !

Actually, in this case, you do pronounce [tooss].
Indeed, when tous is used on its own, meaning "all" (or in front of a vowel), you will pronounce the "s", as it is the case here "Vous faites tous vos devoirs." (You're all doing your homework.).

However, I understand the trickiness here, as this French sentence could also mean "You're doing all (of) your homework", in which case tous goes with vos devoirs, and should then be pronounced [too] with a silent "s".

Here's a link to the related lesson which contains a pronunciation guide:
https://kwiziq.learnfrenchwithalexa.com/revision/grammar/tout-tous-and-toute-toutes-all-all-of-them-the-whole-indefinite-pronouns

I hope that's helpful!