In short, six to eleven year olds.
Every news item has a version for adults and two additional versions. 6 to 8 year olds, and 9 to 11 year olds. However, we don't verify your child's age and encourage you to select the reading level you think is appropriate.
Likewise, you can add older children to any of the plans. The only difference is that they might not benefit as much from the reading comprehension goals.