TQ is Truthquest history. There are samples on their website. They are wonderful guides that take you chronologically through a time period, with booklists and suggested age ranges, and also with some discussion points/commentary along the way. You definitely do not need them, as SCM is enough.
I like them because our kids read a lot, and it helps me make some extra selections; also because we have eight children twelve and under, which sometimes necessitates the oldest working fairly independently – I can have them read through the discussion points in the guide that relates to the area of study if I am simply not available to discuss at that time.
I would warn that Truthquest can be overwhelming for some – if you can’t handle a booklist with a lot of choices, it’s likely not for you. A friend of mine tried to use it and felt they had to read every book on the list, so she ended up selling it. But we like it as suggested reading.
Gaeleen