Were the homework assignments of a type were using a computer to prepare them would actually help? Did the computers include the appropriate software that was needed to do the homework? Had the homework to be submitted in paper form and did the computers come with printers?
http://www.columbia.edu/~cp2124/papers/computer.pdf
The homework assignments are not described, but given that many students do not have computers, it is reasonable to assume that the assignments at least did not require computers. The computer vouchers came with free "educational software", but few households installed it, and essentially no one spent time using educational software, in either group. Printers are not mentioned.