You can see only limited information about a resource in Commons: the resource type and a brief description about the resource. Only when you have imported a resource can you fully explore its contents.
So how do you determine if you want to use a resource before you import it? A quality resource will generally have a well written, detailed description that gives you a clear idea of its content. Another way to evaluate content before previewing is to take a look at the tags. Rich, descriptive tags will help you determine whether the content is relevant. Keep in mind that you can always download to yoursandbox course and that it’s easy to remove Commons content should you decide that the resource is not relevant to your purpose.