These Coloring pages are perfect for teaching articulation!
Print them out and have them on hand.
Teach your student, that for the S sound, our tongue is behind our teeth, so we can's see it. Our teeth are closed and the air flows right in the center of our two front teeth, like through a straw, as we make a snake sound!
Or, you can compare the easy to see mouths so kids can learn the difference between sounds, like /s/ and "th" (sold separately here: https://www.teacherspayteachers.com/Product/Articulation-Mouth-Coloring-Page-TH-1736423 -or- bundled here: https://www.teacherspayteachers.com/Product/Articulation-Mouths-S-and-Th-Frontal-Lisp-Coloring-Pages-Phonology-2201251 ).
As I hold up both the "th" and /s/ pages, I say things like "Put your tongue out for TH, air is soft and flows like mist, but for S, close your teeth and let the air flow straight between your two front teeth." I make sure they understand the difference between the two, focusing on the teeth, lips, tongue and airflow.
Then, I hand out the coloring page and ask them to carefully color all the parts: lips, tongue, teeth and air.
You can have them say the sound as they color.
In a group session, I have the kids color in between turns.
Once the images are colored, I save them for further sessions so that I can point to specific parts on their drawing to remind them which part of their mouth needs to be adjusted.
Full page, easy to see and color.