Do you mean that one child reads a chapter independently and then the other reads the same chapter? Are they happy with that arrangement or do they feel like it’s taking too much time? Do you feel like it’s taking time away from other subjects or activities?
Maybe you could allow them to read 1/2 chapter to each other. Sometimes, if I know my child is getting bogged down, I will read for maybe 15 minutes before handing the rest of the assignment over to them. I always read first because I don’t want to encourage dawdling (“Mom will come read to me so I can be pokey”).
Those chapters are long and have a lot of information, so I understand how it could be taking quite awhile to get through them.
Blessings,
Cindy