Sure! Here’s an activity you can use to help your students differentiate between the sounds /s/, /ʃ/, /ʧ/, and /ʤ/:

1. Start by introducing each sound to the students. You can do this by saying the sound and having the students repeat after you. For example, say “/s/” and have the students repeat “/s/”.

2. Once the students are familiar with each sound, provide them with a list of words that contain these sounds. For example, you can write the following words on the board: “sit”, “ship”, “chop”, “job”.

3. Divide the students into pairs or small groups. Give each group a set of picture cards or word cards that contain words with the target sounds. For example, you can have picture cards of a snake, a ship, a chair, and a jar.

4. Instruct the students to take turns picking a card and saying the word out loud. The other students in the group should listen carefully and identify which sound they hear. For example, if a student picks the picture card of a snake, the other students should say “/s/”.

5. Encourage the students to discuss and explain why they think a particular sound is heard in each word. For example, they can say that the word “ship” has the /ʃ/ sound because they hear the “sh” sound at the beginning.

6. To make the activity more challenging, you can also include sentences or short phrases that contain words with the target sounds. For example, you can have a sentence like “She sells seashells by the seashore” to practice the /s/ sound.

7. Finally, you can wrap up the activity by having a class discussion about the different sounds and their corresponding spellings. You can also provide additional examples and practice exercises for the students to reinforce their understanding.

Remember to provide plenty of opportunities for practice and repetition throughout the activity to help your students solidify their understanding of the sounds /s/, /ʃ/, /ʧ/, and /ʤ/.