One of the benefits of homeschooling is the freedom we have not to assign our kids into a single grade level. We know that grade level in the American public school system is an artificial construct, developed to facilitate mass education. In the adult world, the people in a college classroom, or in an office, or on a construction crew were not all born within a year of one another. We know that within a group of 8-year-olds, skills and knowledge will vary widely. So, we don't need to separate everyone out by age. We can have classes covering multiple grade levels or ages.
We've participated in some multi-age classes and they've mostly worked out well. For the past two years we've been part of a reading and writing group wherein the kids read books, wrote on a variety of topics and shared their work. It was great because each child could work at his own level. The proficient writers encouraged those less so. A piece of writing for our monthly "magazine" could be as simple as a description of a day at an amusement park, or something more involved: a book review, instructions on making a craft, or a complex story. We also read books and shared them via oral reports, posters, dioramas, Legos projects. Of course, there are Legos.
The group of kids consisted of toddlers up to 11-year-olds; most kids were in the 6-8 range. No, the toddlers didn't participate. But, they were always there, in all their noisy glory. Last year a sweet 3-year-old gave her first oral report. I don't remember what she talked about; I couldn't understand much of it anyway. But it was good for her, to get up and speak to this group of kids and mothers.
Multi-age classes are so nice. They are helpful to the mother: all the kids in one place at one time! Learning about the same thing! It's also good for kids to be together with their siblings, and with kids of other ages.
One of my favorite homeschool memories is of our Greek Olympics day, about 6 years ago. Another friend and I were introducing ancient history to our kids, using the same materials, so we got our two families together for some Olympic games. The group consisted of 2 boys, aged 6, a 5-year-old boy, a 5-year-old girl, and a 2-year old boy. Everyone had a great time, especially the 2-year-old who won the applause of all the big kids. On the same day we did this, a friend whose kids went to school told me how her 6-year-old daughter and a friend from her class shunned her 5-year-old daughter while playing. It was, of course, the effect of being in a classroom with kids all of the same age. The younger child wasn't welcome anymore.
But sometimes homeschooling mothers start thinking that there is (almost) no limit to this. Some in our reading/writing group want to start adding more classes into the mix. Science, maybe PE, art... But the mothers of the newly-turned-12-year-olds are pulling back a little. We (as I am one of them) and our older kids are not so interested in a science class with this group. Nor PE. Art? Maybe. The mothers of the younger kids don't understand this. They see how well it's worked before and want to do more. They don't get that the older kids are moving on, growing up. They need something different, not more of the same.
Some topics lend themselves well to wide age ranges; some don't. It's great to have mixed ages and abilities in a writing class; the older and/or more experienced kids can encourage the younger/less experienced while working at their own skill level. The little kids' presentations might be a bit boring, but older kids should be learning how to show interest and kindness to the little ones. The reading projects were set up so that everyone read on the same topic, but not the same book. So when the subject was "boats"- intentionally broad so everyone could find something of interest - the little kids read and talked about picture books like Gail Gibbons' Boat Book; the olders worked with "bigger" books such as Men of War: Life in Nelson's Navy. Everyone had something to share.
But other topics don't work out so well. Can someone really teach a science class that is accessible to 5-year-olds while not being a complete waste of a 12-year-old's time? I'm not talking about particularly gifted little ones, though some of the younger kids in the group are really bright. Nor about severely learning-disabled older kids, though some (such as mine) do have some problems that hinder them a bit. A well-read 12-year-old will usually have a lot more science and history knowledge than a 7-year-old. They are tired of watching baking soda and vinegar volcanoes erupt, bored with making and playing with flubber. They want to dig deeper. They have learned lots of facts about, say, World War II; now they need to connect those facts to the past, and the future.
(Fans of classical education might say this is the difference between the grammar stage and the logic state. Exactly right.)
It is so easy to take something that works and apply it too broadly. The sweet vision of kids of all ages working and learning together is so beautiful, so tempting. And it works well, sometimes. But when it doesn't, we need to set aside that vision and move on. The kids grow up; mom needs to grow her educational plans with them. We may be happy and comfy in our group, but the day comes when we need to step out and find a new one.