Just get a USB Mouse with a scroll wheel. Unless your machine is ancient you can use a regular mouse with it.
Depending on where/how they are trying to play with their laptop, that may or may not be a viable solution. If they're trying to play curled up on the couch with their laptop, they probably don't have a good surface to use a mouse on
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On most laptops there's a strip on the right hand edge of the touch pad that essentially functions like a scroll wheel.
Depending on where/how they are trying to play with their laptop, that may or may not be a viable solution. If they're trying to play curled up on the couch with their laptop, they probably don't have a good surface to use a mouse on