Blends are two or three consonants grouped together, with each letter keeping its own sound. S-blends are highly reliable. When the letters sc, sk, sl, sm, sn, sp, st, and sw appear together as a blend, they will almost always sound the same. The exception is sc, which can be pronounced /sk/ as in scooter or the c can be silent, as in science. S-blends can appear in any position within words. They can be in the initial position as in screen, skate, slim, small, snow, spring, stream, and swamp. They can appear in final position as in disc, risk, chasm, wasp, and mist. The exceptions to this are sn and sw, which only appear in initial position. They can also appear in medial position as in mascara, risking, whisper, and mustard. The exceptions to this are sm, sn, and sw, which do not appear in the medial position.