This is my dd as well. Interestingly, she's also 7 and working in Beast Academy. With her, the issue is simpler. She doesn't want to spend time figuring something out. For her, school is something to be endured and gotten over with as quickly as possible so that she can have free time. If the answer doesn't come to her immediately, she gives up, not because she is easily frustrated, but because she simply doesn't care.
I don't know the answer. :(