Writeacher, you didn't manage to check my post yesterday. I really need your help to rephrase just this part. Thank you very much in advance!

1) Mr. Gradgrind turns his attention to (picks on?) Bitzer, "perhaps because he chanced to sit in the same ray of sunlight which, darting in at one of the bare windows of the intensely white-washed room, irradiated Sissy. For, the boys and girls sat on the face of the inclined plane in two compact bodies, divided up the centre by a narrow interval; and Sissy, being at the corner of a row on the sunny side, came in for the beginning of a sunbeam, of which Bitzer, being at the comer of a row on the other side, a few rows in advance, caught the end. "

"perhaps because he chanced to sit in the same ray of sunlight

maybe he happened to sit in the same place

which, darting in at one of the bare windows of the intensely white-washed room, irradiated Sissy.
where Sissy was

For, the boys and girls sat on the face of the inclined plane in two compact bodies, divided up the centre by a narrow interval;
students were sitting on a slight hill in two groups

and Sissy, being at the corner of a row on the sunny side, came in for the beginning of a sunbeam, of which Bitzer, being at the comer of a row on the other side, a few rows in advance, caught the end. "
(I honestly don't know what this is saying!! As I said before, I cannot stand reading Dickens!!)

1) Mr. Gradgrind shifts his focus to Bitzer, possibly because he happened to be sitting in the same patch of sunlight that illuminated Sissy. The boys and girls were arranged in two distinct groups on a sloping surface, with a narrow gap dividing them down the middle. Sissy, positioned at the corner of a row on the sunny side, received the initial rays of sunshine, while Bitzer, at the corner of a row on the opposite side, a few rows ahead, only caught the tail end of the sunbeam.