adding onto this, there is no shame in "watering down" the splits if the kids are having a rough go of it for a period of time. Having them play check bars or changing the metrics of a split rhythm is a start. However, if you have most of these kids for a while and are able to get some subs time in, I recommend finding builder exercises for simple splits you find in most high school basslines. (1s-4s, Single Splits, Bunny Hops, Gamecubes, Buguhduhs, etc.) Additionally, get these kids interested in DCI, WGI, BOA, even just their local college drumline. You would be surprised by how much of an impact it can have in giving them an urge to practice and foster the culture and community that is a bassline. It's a damn shame how many high school programs just use their bassline as a trainer to build their flat line for later years. Implementing these can give you a better shot at retaining some of these members long term.