Hello Timothy, You will probably want to do your practice assignments in the Mixed Media notebook. However anytime you want to do your official first journal the moleskin one is just nicer, fancier, for an actual record.  When you look at the picking a journal style video you will see that the instructor and some of her real world students used the moleskin style to document their trip to the Galapagos. It is totally optional moleskin but it is perhaps a nicer way or more durable journal based on the cover material.  Personally, I haven't tracked down a moleskin journal yet. However for all my learning and practicing and doing assignments I am sticking to the Mixed Media journal for that. Some people may never use a moleskin  journal. When or if you use it is up to you. Thanks.