Block website during school hours only

This is a Network Security thing not a MDM thing, MDM’s ability to manage webpages is very basic by design as this is a security function not a device management function. Scripting wont help here either.

You need a tool on the network side to block the traffic you are wanting to disallow, when and where you want it disallowed. Many of these Network Security tool have endpoints you can install on devices to make the network controls local, things like ForcePoint, Netscope and Zscaler come to mind.

For what it’s worth, Jamf Safe Internet can do this type of thing. In general ​@AJPinto is correct in that scripting something like this would be a challenge for sure and this is something better served by a tool meant for it. (firewalls and filters, generally.) 

You can limit access to Hudl during instructional hours by using your router or firewall’s scheduling features to block the site at certain times. Alternatively, network management tools like Circle or OpenDNS, or device management policies on school-managed devices, can enforce time-based restrictions without scripting

I think Jamf Safe Internet is the product you are looking for here. There you can have time based profiles, and set up custom filtering. Nowadays kids are using their mobile devices, but if those are locked away during school hours, Jamf safe internet can help a lot on the allowed, managed devices.