Make sure--Does the machine take a short shank presser foot? If so, you can replace it with a short shank zig-zag presser foot. You can probably go to a regular sewing machine repair shop and find a replacement presser foot.
**NOTE--the links below are examples of what is available. I cannot vouch for these vendors as I've never purchased from them. Do your own due diligence before purchasing!!!
Here's an open toe presser foot:
Open Toe embroidery satin stitch foot Low Short Shank Babylock Bro White...
or a regular zig-zag foot:
OR you can buy a short shank adapter and a kit of snap-on presser feet that will give you a big variety of different kinds of presser feet, probably including a zipper foot, hemmer foot, 1/4" quilting foot, darning foot, teflon foot, etc....(probably more than she will ever use!) The snap-on kits are available online, try eBay or some of the other sites. They most likely are not Singer brand, but are most likely generic. However, if your granddaughter is just learning, this may be the broadest variety of choices.
These are examples of snap-on presser feet available.
Snap-on Adapter example (most kits do not include the adapter):
Snap-on kits- examples:
42 PCS Domestic Sewing Machine Foot Feet Snap On For Brother Singer Set...