HOST: So, if I help train a math assistant, why should I care about this? EXPERT: It may help you think it out whether a smaller math-trained model could guide a larger one, and what to measure before choosing a teacher. HOST: Does the larger model just copy the smaller one's solutions? EXPERT: Not in the main method. The student writes its own answer, and the teacher gives feedback on the student's word choices as it goes. HOST: So how did the authors tell whether that helped? EXPERT: They checked answer accuracy on held-out math problems, and they tracked how far each student moved from its starting behavior during training. HOST: What did those training paths show? EXPERT: So what the authors saw was a regular early rise in accuracy. Later on, the paths really varied. Those gains could slow, stop, or even reverse. Their delta-OPD method, though, had a steeper early gain than vanilla OPD in 15 of 17 shared settings. HOST: Could I use that pattern to pick a teacher for any task? EXPERT: The authors don't show that. They studied one model family and one math mixture with one run per setting. The practical lesson is to check held-out accuracy and later training behavior, not just the teacher score or the student's early gains.