Looking again, I think another solution for the second boy in blue would be to get lower if possible and shoot upward. This would have more of the slide in the frame more clearly showing what he is on (my copr totally removes what it is/was).
For this lower shot, I would not show all the slide per se, but enough to show what it is, but still have some space in front of the boy in the direciton he's traveling.
I say all this, realizing from experience that it can be easier said than done to capture kids tumbling down these things coming toward you.