M.S.
This is tough, because it's imperative that the children attend the class M-F for the 10 min instruction, but when it's all said and done you're actually there for 30+ min (10 before class to settle in and get ready, 10 for the class and 10 after, burping & changing clothes) and that doesn't include drive time. While I understand you're situation, my advice would be to explain your issue and see if any one of the teachers are able to accommodate your schedule. Ask them if they know of any ISR instructors that are more flexible. My experience in having similar conversations is that they're really good about recommending one another. If you're unable to come to an agreement, try emailing ISR directly as they may be able to supply you with other options. Just a couple of thoughts.
Our son attends Sheri's class M-F and we're all happy with the class and results. My mornings are hectic, but the lessons are so worth the craziness. We're in Lewisville and when we did our research in trying to find instructors, Mielle & Sheri were the only choices. I just did a search this morning and noticed that there is another instructor available at Frankford & Hillcrest. I'm hoping the list continues to grow.
I hope that you're able to work something out, you'll be amazed! ~M.