Second day on the same lesson — p.11, letters and their sounds in isolation. Do not re-teach it. Re-run the column and go at whatever the children were not accurate on yesterday.
Exactly the same mouth as /s/. Voice ON — zzzzz, like a bee.
They check it: Hand on your throat: /z/ buzzes, /s/ does not. Same tongue for both.
Not in Somali. For those children this is a new physical skill, not a reminder. Do not let the column start until the mouth can make it.