How come my child's summer is job is requiring completion of a Schedule C on her tax return?

[fanfare]

That;s how it works if you get a 1099-MISC.

[xmasbaby0]

Was her pay reported on a 1099Misc? 

If your dependent’s earnings were over $400 and were reported on a 1099Misc then he must file a return and pay self-employment tax for Social Security and Medicare.  You may want to use this version of TT for that:

https://ttlc.intuit.com/questions/1900583-what-is-turbotax-free-file-program