I personally think that 6 is a bit on the young side, but everything with kids is so independent, your 6 year old might do really well and my 6 year old might be in tears because he isn't able to can't keep up with the instructions being given. The animators who are explaining and drawing with you are moving things along at a steady pace and depending on which character you are drawing it can be a little hard to grasp what you are doing, since you have no experience and can't picture how these lines and shapes will all come together to make Donald Duck.
DD and I love to do this activity over and over again. But, we probably started doing this when she was around 8 or 9. She is 12 now. Over the years we have spent many, many hours in the Animation Academy, and for us it is a must do on every trip.
If you do some searching in the web, I'm sure you can find some samples of characters and how to draw them in a similar way. Try it at home and see how it goes. I have drawn Mickey (straight headshot), Mickey (side profile), Minnie, Donald, Daisy, Jack Skelington, Olaf, Phineas and Ferb, Agent P, Pooh, Tiger, and Piglet. Those are the ones I can think of off the top of my head. Like anything, the more you do it, the better you will get.
Have fun!