The letter S the sound of /s/ makes when you see snakes. Hear the sound of /z/ when your nose smells a rose. Letter s is one of the consonants that vary.
s = /s/ at the beginning of words: sand, sell, sip, soft, sun. It is also the sound of /s/ in beginning s blends: scuff, smell, sniff, spill, stop, swim.
s at the end of words can be either /s/ or /z/: cats /s/ and dogs /z/ need baths /s/ with suds /z/. Understanding voiced or unvoiced consonants can help when s comes after a consonant. Consonants that are voiced make a vibration in the throat which can be felt. Consonants that are unvoiced are quieter and no vibration is felt.
After letters made with a hiss or puff of air, the soft sound of /s/ is often there. In these examples s follows unvoiced consonants f, t, k, p, and th: puffs, cups, cats, sacks, paths.
After letters that make the throat buzz, the sound of /z/ is often what s does. In these examples s follows voiced consonants b, d, g, v, l, m, n, r: jobs, nods, dogs, stoves, files, rooms, pens, stars.
After vowels, sometimes s = /s/
The -ss ending flossy words above have the sound of /s/.
More words with the /s/ sound after a vowel: Fill this bus with gas.
After vowels, sometimes s = /z/
Here are some words where s = /z/ after a vowel: It is easy for boys to choose toys.
WATCH videos and PLAY online games at the Consonants That Vary tutorial at Wakelet. Note that many online games require flash and may not work well on mobile devices. Downloading the Mozilla Firefox browser can be helpful.
Letter S is covered in Consonants that vary (IV.c) in the Phonics Pow Toolkit with a worksheet and gameboard. Learn how to get a free set of word sort games that includes the two sounds of s. A free word sort game for the letter S is available at the Super Tutor Tools store at Teachers Pay Teachers.