I am about to teach a class with a laptop attached to a big screen.
I wish to have the mouse bigger, and with some yellow marker on it.
What (free) software is good for that (for windows) ?
ZoomIt allows you to to draw things and zoom on your screen whatever program you are using.
If you choose a lower resolution while presenting, you will also get a bigger mouse.
If you are using Powerpoint slides, you can write on the slides with a pen.
I would suggest walking to the back of the class before a lesson to see how big the mouse really is...
A Freeware software does indeed exist to create custom mouse pointers.
The site also features custom cursor gallery, you can have a look if you find something useful.
Control Panel : Mouse : Pointers : Browse... and select a .cur file that you like.
I think these are actually .ico files and if so you should be able to edit them with Microsoft Paint.