What is "sch-"

this letter group can represent five distinct sounds in English; it first was used by Middle English writers to render Old English sc-, a sound now generally pronounced (and spelled) "-sh-." Sometimes it was miswritten for -ch-. It also was taken in from German (schnapps) and Yiddish (schlemiel). In words derived from classical languages, it represents Latin sch-, Greek skh-, but in some of these words the spelling is a restoration and the pronunciation does not follow it (as in schism).