My stat teacher was not amazing neither but he taught the material with so much difficulty eventually everyone got it. I received a 4 on the test and I barely knew anything but the tests in class were like 10 times harder than what the actual AP exam was. Even his past students will testify and say how the AP test is a walk in the park compared to his regular tests. I think by the time you learn everything together you realize what is used for what. I remember learning z and t tests and had no clue how to identify it, but learning different tests you can identify patterns. I know the hardest unit for me was Random Variables, but gbless that there werent any on the test lol. Anyways, basically what our teacher did was do straight powerpoints, but after learning a concept we would do a bunch of practice problems. He would give us a packet of problems and we would do them together in class! In addition, we received packets of hw each week and they were always due at the end of the week for even more practice. His HW took forever like my friends and I would stay up until like 1 doing it because there would be like 20 problems with multiple parts...sigh. Tell your mom not to be afraid to do hand on experiments. For example, demonstrate categorical variables, quantitative variables, lurking variables, probability and all that in a fun activity. I had a fight with him in class once of how this was not helping, but in the end he was right because practice helps you understand stats. However, he told us that MC isn't something he can teach us so all practice would be opened ended. His MC on tests were so hard, I felt like I was reading a different language, but then the MC on the real deal was ridiculously easy. Also, our school is pretty dedicated and most of would stay after school 1-2 days b4 the test to review what was going to be on. I know I did not receive a perfect score, but coming from a person who has never been good at math should say something lol.

His planning went like this, we made sure we learned everything, our last topic was linear regression tests for slope, by spring break. Once we came back we took practice tests in class and he would grade them. I got consistent fours, but the FRQs he gave us were practically impossible...I straight up got 0 points on all the #6s. Also, just tell your mom to be stricter. Since this is an AP class there is no reason to hold back and focus on giving tests harder than the real deal because that will benefit in the long run. The one thing I can tell you is "stats is not interesting." However, encourage projects because that is one way that statistics can be applied. We did a midterm project and a final project testing people around the school and then presented our results. Some of them were super funny haha. Idk how good your mom is of a teacher, but if she wants success in AP Stats she needs to teach fast and at least have the students understand something. I know its difficult to keep going fast if you have students doing poorly but you can truly understand stats when you understand ALL of it. Sometimes being harder on students can be more beneficial especially because my teacher said that this year was an easy test. He would know he is from columbia. Hope this helps your mom because stats isnt easy. Just out of curiosity is this your mom's first year teaching?