WARNING! Science Ahead!
Drywall and chalk are basically the same chemically, both are Calcium Carbonate, which may be why the chickens are attracted to them, their going for the calcium. However, as others have mentioned, either may contain other ingredients that could be bad for the chickens. The chalk, if it's a natural chalk (as in rocks) might be OK.
However as grit both are useless as they're too soft.
Drywall and chalk are basically the same chemically, both are Calcium Carbonate, which may be why the chickens are attracted to them, their going for the calcium. However, as others have mentioned, either may contain other ingredients that could be bad for the chickens. The chalk, if it's a natural chalk (as in rocks) might be OK.
However as grit both are useless as they're too soft.
