So right, digging potatoes is a treasure hunt! Anne I've been volunteering at the local elementary school where we have a vegetable garden. We grew purple potatoes last fall and this spring we have yellow ones!
The youngest kids are in kindergarten, so they are mostly 5 years old. We keep the sessions short, and think of a quick project each time the kids visit that will hold their attention. They are usually in the garden about half an hour.
The first thing I'd recommend is seeing if you (or mom) can get a pair of little gloves for the child. A magical thing happens when kids put on gardening gloves - they want to dive right in and dig a hole! (Another thing we found is that kids in Florida don't know how to put on gloves, but that's another story) We teach the 'basics' in words of one syllable i.e. "what 3 things to plants need?" Sun, water and soil. "what part of the plant collects sun?" the leaves . . . etc.
Getting up to 3rd graders we start to teach the 'real' theory of things like photosynthesis, but for the little kids it's just "The sun helps the plant make food for itself and for us".
Little kids like to plant big seeds that are easy to handle, like peas and beans. Beans have been the most fun plant we've had in the garden because they germinate fast, grow fast, produce a lot, and down here they always get bean leaf rollers. Don't forget that a pest on the plant is a learning opportunity - kids love to unroll the leaf edge and find the caterpillar hiding in there. Then we talk about why we can't let them eat up our bean leaves - again, the plant needs its leaves to make food. Oh, and when we first found the leaf rollers, I made a boo boo when a little person took the caterpillar off the plant and asked what to do with it. I said "oh, just drop it and step on it" You should have seen that little face !! Now we throw them over the fence into the grass field - "set them free".
That leads us to talk about what we can do to prevent bugs, critters and birds from eating our plants. Soapy water, baking soda solution and Bt are all we use in our school garden so it's easy to explain even to the little ones that you only use things that are not bad for people, animals and the environment. etc. etc. We also talk about good bugs and bad bugs a little bit i.e. "do you think a spider is good or bad in the garden?" "do we want a snake to be in our garden?" We have a little corner with butterfly plants, and we also talk about why we need butterflies and bees to come to our garden.
Let the child do weeding, and show them how to recycle the weeds into compost. At the end of the school year, our most fun day is when the kids come out to clear out the garden. They pull out the plants, cut them up into pieces and pile them into the compost. Then when they come back after the summer, they are amazed that all that plant material had reduced down to beautiful new soil!
Last thing, also see if you can find a really small watering can. Get one with a 'rose' that sprinkles, not one that pours. Again, long faces if a big stream of water knocks down a seedling! We say "water gently like the rain" and that works. Kids just LOVE to water! We got 2qt. watering cans at Home Depot that are a good size for kindergartners, but still we don't fill them right up, as they're too heavy and the kids struggle and spill.
