I homeschool and have 3 kids. 8, almost 6 and just-turned-3. All I can say is good luck:)...it will be better next year LOL. It's hard. I know when my little guy was that young I could turn on the TV and he'd watch for a while, wonder in with us and I'd have a toy he hadn't seen in ages all ready to whip out and that would occupy him for a bit, then I'd give him a snack that took a long time to eat (dry cheerios or some small finger food) and that would get him out of our hair for a while :) He was (is) a very busy guy that even at that age could un-do babyproofing so I was constantly getting up to see what he was doing. My mantra was "this too shall pass".
Luckily when he was a year and a half one kid was in Kindy and one was in second grade. The kindy would finish first and go play trains or hot wheelz with the 1 year old and that helped me to work with the 2nd grader. I oldest was really patient about waiting to do the more intensive stuff when the youngest was napping.
We started school last Monday and (so far!) things have been awesome. So, take a deep breath, know you are doing the best for your kids (and things will get easier), and bribe if necessary :)