You have a lot of great suggestions here. I would second getting a full size machine. I started sewing at age 8 on my grandmothers full size 1946 singer, a straight stitch machine w/reverse. Once I started, I never looked back but have found the need to upgrade to machines with more functions over the years. Janome makes really decent machines with multiple functions for very little money as I'm sure most brands do. You can get a good quality machine with basic stitching, zig-zag and some embroidery stitches for around $200 dollars. Remember that they will probably use this machine until they are adults and are able to purchase one of their own. You are a wonderful mother for teaching and encouraging a craft that will last them a lifetime! Best wishes.