I am so often asked for ideas for things that can be made by children, or indeed, adults, who want to learn to sew, that I thought I should write up some of them. Here, I will be focusing on children, but many of the projects I suggest are equally appropriate for adults. There are one or two ideas here for things that can be hand-stitched - well, almost anything can, it may just take longer! But I would almost always suggest that children learn first to do some hand-stitching before attempting to use a sewing machine. That way, they will learn some techniques which will always stand them in good stead.
Of course children can be different ages and in different circumstances when the situation arises. It's different teaching a five-year-old from a ten-year-old. However, I'm not going to offer any advice about what age is appropriate for a child to use a sewing machine, or what machine to use - you know your child best. I personally think simple is better to start with. You might want to get a guard for the machine, though, especially if the child is young.
Constructing a sewn item can also teach several skills: mathematics, to calculate sizes and seams etc; design; following written or video instructions; taking care of safety; and of course fine motor skills. And there can be so much satifaction at producing a usable, wearable, or fun item.