ditto pink bunny. vmware and virtual box are two of the more popular apps that let you run a "virtual" copy of an operating system "inside" your main system. I run MX Linux these days, but sometimes I have an app for which I need MS products. I use a virtual box (I echo pb's support of vmware, it is better and I used it for years) install of windows 10. I so seldom use it that I will download the iso from microsoft, install it, use the app, save the end product and just wipe it and reinstall if Gates and company whine too much about needing to "authenticate" it.
If you have an older machine, I would not recommend trying to run a virtual machine, as the demands on memory are pretty intense. Your machine is literally running TWO operating systems at once, one "inside" the other. However, depending on what apps your son needs, you might be able to get by with running some linux distro and a windows "emulator" (a program that allows linux to run windows programs "natively"). The WINE emulator does pretty good with some stuff, not so good with others.
As a final alternative, you can find lots of Windoze 7 copies out there on the web for very cheap.
Hope that helps.