We try to do Nature Study at least 2x a month. It usually works best for us to have an afternoon each week that we alternate between library and nature study.
I have a small toiletry bag in which I keep our journals, pencils, erasers, and colored pencils. I can easily throw this small bag into my backpack with a picnic blanket and water bottles, and off we go.
Moleskine Plain, Kraft Brown, 5 x 8.5 inches are our favorite journals. They are easy to pack, durable, and stay folded open for drawing.
Prismacolor Pencils are our favorite tool. They are expensive, but very good quality. I buy them with my 40% off coupon at Michaels.
Many families also use:
If your children are really averse to drawing, let them take pictures of things they find. At the end of the year, assemble them into a field guide for plants, birds, leaves, bugs, trees, etc, showing specimens and seasons. Have a real photo book printed (on Snapfish, etc) as a keepsake.
Nature Study Websites
The website Handbook of Nature Study is a tremendous resource. If you get on their mailing list you will routinely receive links to download free materials for nature study.
Find something from every letter, A-Z, or spell out a word like a name, holiday, etc.
Five Senses Hunt
Find something for each of the 5 senses. See a wildflower. Smell the jasmine. Hear the wind blowing in the trees. Feel the sunshine. Taste some honeysuckle.
Find objects to match color samples. You can use crayons, paint sample cards, or an egg carton with each compartment painted a different color. Younger children can use simple colors like brown, green, grey, purple, etc. Older kids enjoy finding different shades of green or brown (paint sample cards are very useful here).