Choose the reading you want. You can switch at any time.
They all teach the same thing. Every level covers New England, the Middle Colonies and the Southern Colonies, and every level teaches the same seven words, so your table can talk about the same ideas no matter which one you picked. The longer ones say more about why things happened — they are not about being smarter.
Pick the one you can read comfortably. If it feels too hard or too easy, switch. There is a level switcher at the top of every reading.
Listening to it. Every reading has a Listen button at the top. It reads the page out loud and lights up each sentence as it goes.
Reading it in another language. Right-click and choose Translate to… Everything is real text, so the whole reading translates, including the meanings in brackets.