The T.E.S website has a host resources that are free to download. You simply need to register and then you can download a host of ideas/ resources etc.
This link takes you to a really helpful pack of ideas and recipes that you can use with a range of children - I like the 'Snow', 'Slime', 'Clean Mud' and 'Fruit putty' mixtures.
If you are working with young children or students that require sensory support -this pack would be well worth downloading.
Pack of Sensory play ideas/ recipes