how do I input data for a switch parameter?

Complete newbie to powershell...I have set a parameter to be mandatory, but I am not familiar with the input format to make it work. My parameter looks like this 

[Parameter(Mandatory = $true)[switch] $isValid

now when I run my code and it asks for the input value for $isValid, what is the right syntax? So far i have tried just typing "$true", "false", "1", "0", '-isValid"(all without the quotes), but it doesn't accept anyone I have tried to put in. Any Ideas how I can get my code to accept the input?