There is no exact answer to this question. We start the kids as early as 5 years old, however, if we notice a prolonged struggle, we quickly shorten the project and move on. You can keep coming back to it every six months or so. Never force the issue, they will grow to resent knitting. Alternatively, don't let them give up too soon. They will absolutely be frustrated at first and you need to teach them that frustration is part of the process and it will get easier. If it's still frustrating after 5 or 6 different attempts, then you could move on to finger knitting and let them practice their fine motor skills. Keep the sessions short at first, especially for the little ones. Put them on your lap and work together for 15-30 minutes. Obviously if they pick it up easily, let them tell you when they are finished. By the time most kids are in second grade, they can pick up knitting very easily.
There is currently no hard research on the benefits of handwork. Universities are now just looking into the correlations, and data should be out by 2009. What I can tell you is what I have experienced. The biggest benefit I have found is the confidence children derive from their creative accomplishments. Kids just love their finished projects and take great pride in their work. Think back to when you took home economics, do you remember the A line skirt you made (or whatever project it was)? Most people I talk to either remember or still have those handmade projects. Also, handwork really helps develop fine motor skills. The repetitive nature and the fine tools they work with help with finger manipulation. Additionally, math and reading are widely used in handwork. Whether reading a pattern, increasing or decreasing stitches, or working on fractions with machine sewing, kids must think as a part of their crafting. If your child is not into sports, dance or athletics, needle arts offer another gratifying means of expression. I used to say that handwork was a non-competitive activity, but I have since come to learn that the kids go at it line for line and stitch for stitch trying to be the best and fastest. Oh well. A benefit that adults talk about with handwork is the sense of peace they have when creating. If you want your child to have crafting to go to as an adult, start them when they are young. The likelihood that they will carry needle crafting into adulthood increases dramatically if they start before the age of 10.
If you think your child will have some kind of sustained interest in machine sewing or if you think you will use a machine, then I think you should make an investment in a fairly good but basic machine. You can spend under $200 for a new machine and it could last your child a lifetime if properly maintained. I never recommend "kids'" sewing machines. The frustration they will experience with a plastic or cheaply made machine could cause them to lose interest in the craft. You also don't want to put them on an overly complicated machine that is highly computerized. This too can cause confusion. At the studio, we use a well recognized brand but buy their most basic model. These machines get a lot of use in our classes and camps and hold up fine as long as I take them in every year for a tune up. If you yourself don't sew, I would recommend buying your machine from a sewing machine store. They generally offer a free class with the purchase of the machine to show you how to get started. Both you and your child should attend that class.
We originally started teaching kids in second grade, but quickly changed it to third grade in our second year. If you have the time and patience to sit with your child, you can introduce them to sewing as early as 5 years old. They can press the foot pedal while you sew, or they can help with pinning. However, if you want your child to have a more complete sewing education, where they can enhance their sewing by reading and understanding instructions, then third grade will be the easiest transition.
We have a rule in the studio that our teachers cannot teach their own children. For you home schoolers, taking instructions from parents is a non issue. However, for the rest of the world this can be complicated. So, if you have a grandparent who could teach your child, that is a great way for them to bridge the generational gap. If you are not so lucky, you can ask your local shops (see our retail directory for shops in your neighborhood) and see what classes they offer for kids. If that doesn't work, ask your friends. Someone usually knows someone who knits, crochets, embroiders or machine sews. See if they will give private lessons. Just let go of the fantasy of sitting fireside and knitting together and don't be insulted. It is very common for kids not to want to take lessons from their parents. My suggestion is to just keep crafting and if they are curious, invite them to partake but don't push it and NEVER criticize their work. Just tell them how beautiful it is! Remember: skill comes with age and practice!
You can't or I should say, you shouldn't. Our overall purpose is to teach the children so that they enjoy crafting and want to pursue it over a lifetime. The easiest way to crush that spirit is to overcorrect them. Remember how you felt when your mother tried to tell you how to do things, regardless of whether she was right or not? I believe that the process is more important that the product. The children derive tremendous pride from their "finished" projects--even when they're unrecognizable to everyone BUT the child. As long as they keep crafting, skill will come with age and practice. We sometimes have a "knitting fairy" or "sewing fairy" or "embroidery fairy" come and "visit" a project (even the older kids laugh at the notion) if the child is becoming increasingly frustrated by a lack of progress.
For the most part, yes, an old machine is sturdier than the machines they make today (just check that the electrical cord is still safe, my grandmother's frayed over time and became a hazard). If you receive one as a gift, I would suggest that you take it to your local sewing machine repair shop and ask them for a tune up. Also, see if someone there can offer you a lesson to familiarize you with the machine. If you need an instruction book, go on to ebay, where you can often find a copy of the manual for the exact make and model of your machine (gotta love ebay). If you are not sure, I've found that the sewing machine repair shop can help you make the judgment call about the machine's overall usefulness.
Again, same answer, you can't or shouldn't. Over the last seven years I've come to learn that kids learn and craft differently. You should take yourself and your habits out of the equation. A perfectionist needs to be a perfectionist and you can't force them to relax. I give the perfectionists in my classes two options; live with the work as it is, or undo the mistakes and I will help you put the project back together. The perfectionist will generally take the second option. For the child who is quicker and just wants to finish a project regardless of the outcome, their complaints are met with the same two options. They generally take the first. Again remember it is the process not the final project.
I am proud to say that we have never had a serious injury that required anything more than a bandaid. That being said, we also watch, teach and prepare the kids very carefully. You certainly never want to leave a 5 year old child unattended with a sewing needle, felting needle or scissors. Many, if not all of our projects use these items and are meant for children age 5 and up. We strongly recommend that parent or adult supervision be a part of the process. Also, getting your finger pricked on a sewing needle or pin is part of the learning process. I do it to myself all the time. Just don't make a big deal of it, stick a bandaid on the "hurt" and move on!