Once upon a time I was a single dad attending college full-time. Mom and Dad didn't live nearby, her mom had left her, nor did I have other resources to assist my 3-year-old daughter and me during this demanding time- we were on our own.
It was a time of lots and lots of homework and sacrifice. The studying significantly affected the amount of time with Ariel, and she in turn started acting out. At first I got frustrated because I didn't know what to do. I recognized the frustration, and instead of getting mad at Ariel, I realized that I could try something different.
I pulled out the timer and told her that I get 20 minutes of study time, then when the timer goes off, she gets 20 minutes of "Daddy-Daughter Time". She got to pick the activity. This was presented in a happy, fun way. I wasn't sure if 20 minutes was appropriate at first, but it sure was.
After one hour, she totally got the concept and loved it. I was completely left alone to study every 20 minutes, and alternately was totally devoted to her every 20 minutes. No scolding occurred. No one got antsy. It was great. I think one thing that helped out was that she got to think about what activity she wanted to do; letting her make age-appropriate choices made a big difference.
I also found out that I studied much better by going all out for 20 minutes and breaking for 20 minutes. I got more done in half the time and had and easier and more fun time of it!