Puppies (even adult dogs) thrive on silliness and high pitched praise in much the same way that human babies thrive on peek-a-boo, funny faces, and cooing. Humans are hard-wired to respond to babies (of all species) in that way for a very good reason. In the early development stages, these actions are crucial to developing bonding, communication, mimicry, and recognition skills. This phenomenon has been noted in other species as well.
Dogs have developed, through many thousands of years of natural selection and breeding, an uncanny ability to read and respond to human verbal intonations and body language, which surpasses any other species, including apes. And like human babies, they are much more likely to learn and respond favorably when exposed to happy gestures and voices and rewards.
Too often, we think of obedience/manners classes as a regimen of exercises instead of something enjoyable that you get to do with your dog. Your dog will respond quicker and with much more enthusiasm if you make it seem like play. Training should be fun for both of you. If it isn't, something is wrong. Sing to your puppy, squeak or grin at him, jump up and down when he does the littlest thing right (or even just a bit better), just make it fun.
I have not read the book you mentioned, but it sounds like all of the fun has been taken out of training and building a warm relationship with your pup. I agree with Cindy that those methods are ridiculously outdated and set back training to an archaic time when humans resorted to bullying as a method of achieving everything they want. I suspect that your puppy may become bored to tears or unhappy with his training if you leave out the joy.
I do think that a 75 minute session is too long for a wee pup, but remember that you have the option of taking several breaks during the class. I am assuming, however, that a portion of that time is devoted to free play/socilaizing with the other pups, which you do not want to miss. If not, you can leave the building and go for a short walk, some play/bonding time, a pee break or just let your puppy rest while you watch. Remember that you control what happens in class, not the instructor. A good instructor will trust your judgment if you need to take breaks and will fill you in on anything important that you may have missed. And it sounds like your instructor is tuned in to your progress/needs, since she is emailing you with questions/advice.
Keep in mind that a 12 week old puppy has a very short attention span and typically has short bursts of energy before he needs a rest. Training sessions at home should be no longer that 10 minutes at this age.
Whatever you do, don't bore your pup or stifle his natural enthusiasm by being regimented in his training. How you approach this now, will be the basis for how eager he is to learn in the future.
