Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
prae-disco, ĕre, v. a., to learn beforehand, make one’s self acquainted with beforehand (rare but class.): aliquid, Cic. de Or. 1, 32, 147: ventos et varium caeli praediscere morem, Verg. G. 1, 51: sic ut praediscere possimus, utrum sit perseverans, Cael. Aur. Acut. 2, 18, 104.