Beta means B for backwards. I always liked that accidental coincidence in the ISI curriculum. Aside from backward swizzles, this is the first place that sustained backwards skating is introduced.
By definition, backwards crossovers are a continuous backward movement around a circle, pushing with the “outside” foot, then crossing it over the “inside” foot; the crossed foot then pushes to the outside of the circle (the “undercut”), and returns to the starting position. To pass, you must demonstrate a strong first push without dragging the toe pick, smoothly lifting that foot to cross the skating foot, and pushing to the outside of the circle with the second foot. (USFS Basic Skills teaches cutbacks, i.e., no lift. More on that in a minute.) Five consecutive cross-overs are required to pass, with no additional pumps or pushes.
Backward Stroking is also in this level: Continuous alternating backwards pushes along an axis. Finally, Beta includes forward T-Stops (right and left): A one-foot stop in a “T” position, using the outside edge of the rear foot to stop. To pass, you must be able to use either foot to stop and you must be able to come to a complete stop after three strong pushes.
Throughout the ISI curriculum, a great deal of independent thinking is required on the part of the coach. Inexperienced coaches will jump in on the first day of Alpha or Beta with crossovers, forgetting that you can't do crossovers with a hinky one foot glide. The USFS Basic Skills curriculum solves this by making testable skills of one foot glides and pumps around a circle, forwards (Basic 2 & 3) and backwards (Basic 3 & 4). Unfortunately, these skills are in the levels BEFORE the crossovers. I also think Basic Skills gets it backwards, teaching pumps before edges. You can't do a proper pump if you don't know how to balance on a curve (i.e. edge). Further, separating these skills disguises their connection to each other. You'd be amazed at the number of kids who tell me there are no one-foot glides in crossovers.
Cut backs, with no lift over, are actually correct backwards crossovers. High level skaters don't generally lift the foot on back crossovers. However, in the lower levels, unless you're in a program that's willing to let a kid languish in Beta for a while, it's difficult to start with the tricky weight shift in a cut back when you've never done back crossovers before. Unfortunately, ISI does not then put cutbacks into the curriculum farther up, and some coaches expect the kids to just pick it up, or to learn them in private lessons. (ISI, are you reading this? Can you please add a pre-freestyle level for cutbacks, moving turns, and stationery spins? Thank you.)
Unlike at the Alpha level, where "correct" is good enough to pass (i.e. a "C" grade or even a D), your Beta skater should start working towards As and Bs. Coming out of Beta, the skater should be starting to use backward crossovers to generate power. This means no toe scraping, and a clear understanding of how to generate the underpush. Not every teacher will continue to work on crossover skills in the following levels, so if they don't learn it here, they'll suddenly turn up in a freestyle class in a few months with everyone whizzing past them. Personally I think Beta should be divided into Beta 1 and Beta 2, but no ever asks my opinion, for some reason.
So how do you generate the underpush? The key is to sink down as you stroke through. Watch a low level freestyle or under class sometime. You'll see kids nicely bend their knees for the first pump, and then straighten up as the leg crosses under. Crossovers bend down and then down again. (Can't use your knees for power if they're straight, after all.)
Bend your knees. It's what the title of the post means.