Strength Training & Calorie Burning Questions

Hello all,
I am new here. I don't know all the in's and out's of MFP site. So I had a question on how the exercise tracker works. I have started doing strength training dvd's and really feel the burn. I know I am burning a good amount of calories working out for 30 minutes at a time, plus warm up and cool down. I noticed I can find cleaning, gardening and just about every other activity I wouldn't have thought to count previously as "exercise". So why then when I do real exercise like squats, and crunches there is nothing showing what calories I have burnt. That seems a little off to me. I don't feel like it is giving me a full picture here. Can anyone explain to me why it is set up like this? Thanks.