The first thing you need to do is to find the location where you will be taking the kids on a nature walk. The nearest park or an easy hiking trail will work great. It is recommended that you search for a place with lots of flora and fauna, and a suitable walking terrain. Make sure you map out your route before you head out.
Choose a track which is suitable to the age of the kids; for instance, if the children are very young, you might to select a short but interesting track. During the walk it is important to constantly keep an eye out for weariness - if the kids show signs of getting tired, take a break and have everyone sit down for some snacks.
Some kids hate walking, so you need to be clever about this - get them excited beforehand, or tell them that the person who, e.g., gathers the most flowers, will get a candy box at the end of the track. You can also have everybody sing songs as they walk, or amuse them with a story.
What you wear is an issue that needs your special attention, as kids need to wear comfortable shoes and weather appropriate clothes. Long pants should be preferred if you plan on walking in long grass. Always cover the kids with plenty of sunscreen, to avoid painful sunburns.
Bring things that will keep the kids occupied and happy, for instance you can bring along a bird identification book, binoculars, a magnifying glass etc. All these things will make the walk a lot more interesting for the kids. Children are fascinated by wild animals and birds so if they are able to spot a rabbit or a parrot, they will enjoy the experience thoroughly.
Encourage the kids to explore, look under the rocks, up trees, and all around them to enjoy nature and find something interesting. Kids will enjoy foraging under trees, bushes and rocks for interesting creatures.
You need to make sure you take the lead and teach the kids a thing or two. You can teach the kids all about poison ivy, e.g., by telling them how it looks and why they need to stay away from this plant.
If the kids are old enough to handle a photo camera, let them take pictures of everything that amuses or interests them. This is the best way to preserve the memories of the nature walk.
You need to carry granola bars, fruits and bottled water for everyone, as a long walk will make everyone hungry, which can also put the kids in a very cranky mood. If the kids get hungry and are not given anything to eat, they will probably never want to go on a nature walk again.