I've been doing guided math, and wanted to mention some technology that I've found works well for small-group instruction.
There's an old laptop with OpenBoard installed, connected to a donated 32" TV. We use a Wacom Bamboo pen tablet, but any similar tablet would work. I also like the Windows 10 Ink tools, the Bamboo Paper app, and Microsoft OneNote. We've also experimented with tablet computers or iPads and and rubber styluses, but they don't feel as nice to write and draw with.
I also have a laptop with a spreadsheet for anecdotal notes on student progress. It's angled so that only I can see the screen, and I make sure to take it back to my desk when we're not doing guided math or guided reading.
So it's not anything groundbreaking, but it's technology that's working well for us.