The truth is, sometimes she doesn't. "Last week I had to console my son, who was having a nightmare, in the middle of a timed assignment," she says.
Managing motherhood, uni and work commitments requires considerable family support, precise time management and dedicated self-care - something this active 40-year-old has learnt from experience.
"I've studied on and off (first law, then paramedicine, pharmacy and now science) for 13 years, so I've become used to chaos, but there's no perfect time for a mother to study," Penny says.
"If you were to put everything on hold to study, you would miss a big chunk of your children's lives. You have to take the plunge and make it work, and ensure you are doing it for the right reasons.
"Time management is critical, and accepting the need for sacrifice. My time is never wasted. I use small goals like visiting friends or going kayaking with the kids as motivation, and I hold myself to it."
So what does Penny's average week look like?
"Mornings are family time and the day is work time. When I get home, it's family time (homework, baths, dinner and reading) until the kids go to bed, then I study at least until midnight.
"I try to limit study to nights on the weekend. Self-care is very important and I try to fit in running, time with friends and listening to music."
However, the schedule doesn't spare Penny mother guilt.
"I still worry about missing school assemblies, but life is not that structured and perfect," she says.
"Being a good Mum is not about being there 24 hours a day; it's about making the most of the time you do have together and ensuring your kids have all that they need."
And university study can impart valuable life lessons for all. "It's important to me to set the example that there is no reward without hard work," Penny says.
"Sometimes I complete a big assessment and we're all cheering. I hope my kids are learning how to prioritise, how to adapt and re-evaluate.
"A family is not just all about them or me, but about compromise and working together. There will be disappointing days - that's life - but I think they see that what I am doing is to better myself and our family.
"It's not always easy and it's important to have reasonable expectations. I've had to let some things go. Doing home reading with my kids is far more important than cleaning the bathroom."
Penny will soon commence her honours year. She also works full-time as a project manager within UNE's Faculty of Science, Agriculture, Business and Law.