This level focuses on verbs that change to have an -aught, -ought, or -ept ending in the past tense.
The tricky part is discerning between when to use -aught vs. -ought. One rule of thumb: if the present-tense verb has an a in it, use -aught. If not, use -ought.
So teach and catch become taught and caught, but bring, buy, fight, think, and seek become brought, bought, fought, thought, and sought.