I suspect she has covered it.
She is doing fractional indices on the second page (x to the power of half is the square root of x ,etc). She is not going to be doing that if she hasn't done the straightforward index rules of adding powers when you multiply, and subtracting them if you divide.
She will possibly have done it on a topic on simplifying algebra or something, and learning to write things correctly in algebra - ie., knowing that if you have bxbxb you write b-cubed, and knowing that anything divided by itself is 1, so b/b = 1. If you do b times b, and then divide by b, you're just left with one b again. If you do b times b times b, and then divide by b, you're left with bxb. And so on. Each of the b on the bottom 'undo' one of the times you multiplied by b on the top. This is just an extension of simplifying fractions, and she probably did it ages ago on Sparx as they have lots of questions on that, before you really start to get into the ones with lots of powers.
Once she understands the basics of doing it with just lower powers that you can write out, they give almost exaggerated questions with large powers so that the students realise that the same principles apply. If they understand the basic ones, the bigger numbers are no harder. A number to a power that is then all to a further power is again just an extension of this.
You would definitely do all of that before you start to do things like why x to the power of half means the square root of x. So I would bet that somewhere in her book, there is an explanation of this, long before she got to do the stuff on the page on the right.
Sparx is quite good at bringing back old topics into the homeworks, to make sure that people don't forget that material, and that's one thing I like about it. It's up to the school what topics are put into it, though, so if the school aren't using it well, that's something to bring up with them.