standard versus brightness

I've been thinking about how to solve the problem that some children start with more comprehension than others but still need to learn how to read and write. How can schools give each child the material that fits it when there are huge differences between children, to start with on text comprehension. There is differentiation on the level of technical reading, but not on the level of comprehension. This would mean the necessity for a complete new line of schoolbooks that are high on comprehension and low on technical reading.
Standard levels may be useful for schools, they may be useless for society. There are complaints at Universities and colleges about the levels dropping. What I observe is that the brightest children drop out and the level at the end of the secondary school is too low in the eyes of the Universities.