An easy elementary science project to do with the kids is show them the root systems on plants. It will give them a better handle on how it looks like in the soil below the part of the plant we see. You can make a root view box.
There are some commercial sets, but here's how to make your own from a few common materials. We used a plastic cat litter container. It was fairly easy to cut. We cut the container so it was about seven inches tall. We cut out a section in front, another rectangle so that we would have a window. We then taped heavier plastic to it to make the window. We used plastic from a Barbie doll box. You could use any plastic as long as you can see through it and it can withstand some pressure from the soil you will add.
Add soil and seeds. We watched corn, peas and sunflowers grow. You have to make sure you place the seeds as close as you can to the window. After you plant the seeds, place black construction paper over the window to keep it dark. You still have to put the root viewer in the sun or under artificial growing lights.
The kids took notes on how the roots looked each day. They were excited because they actually got to see the roots growing.
It was a great experiment. After a while the plants got too big for the container and we had to throw them out. Next time we might try transplanting them to see if they continue to grow.
Do you love to give plants as gifts? If so, you may find that some of the recipients are frustrated by having to care for a plant when they have black thumbs. However, you can give your friends and family plants that are virtually impossible to kill by making a simple terrarium.
Gardens grow, then they die. These natural cycles are something a younger child might need help understanding. Here is some information to help kids understand that gardens have needs, much the same as all living creatures do.