The Chicago Area Orienteering Club (CAOC) offers events (meets) on Sundays approx. once a month (twice in some spring and fall months, but none in July). Upcoming CAOC events can be found on their calendar, along with a contact who may be able to confirm the course length and who fields inquiries from individuals interested in being a course setter (required for the Orienteering Merit Badge).

CAOC welcomes newcomers and always offer a free beginners clinic prior to their competitive meets and include a beginners courses.  From their website:

CAOC offers a beginner's class at 9:30 a.m. at every meet. The 15-minute class is repeated as needed throughout the morning. The basics of orienteering are very simple. Most people believe orienteering is a compass sport; it is really a map sport. The skill is in matching the map to the terrain around you.

After the clinic, beginners generally navigate a White course, which is: “For the beginner. White is suitable for adult and teenage novices. Younger children should be accompanied until they have learned to navigate for themselves. White courses are 1.5 to 3 km long, measured in a straight line from control to control. Your route will be longer than the straight-line distance. The course follows trails and controls are placed on major features. Before starting you should know how to interpret map symbols and colors and how to orient the map to North. There are always club members available to teach beginners how to interpret the map.

[If the White course is too short at a particular meet, there is usually also a Yellow course]: “For the advanced beginner who has experience on White or has done a lot of hiking with a topographical map. Yellow courses are 2.5 to 4 km long and mostly follow trails but some controls are located in the woods just off a trail. Before starting you should know how to select and follow a ‘handrail’ such as a stream, how to select and use an ‘attack point,’ how to interpret scale and judge rough distance, how to take a rough compass bearing, how to select a route choice (safer vs. shorter), and how to recover from an error by backtracking to the last known point.”For more general information, please visit: https://chicago-orienteering.org/intro.htm

CAOC's scouting contact advises:

It's difficult to pin a completion time, as course lengths can vary with the location and the setter, but since the event formally starts at 10:00, and most white courses tend to run about a half-hour to an hour, depending on skill and speed, I'd say a safe guess would be: done by 11:00.

You can “just show up”. It might be to your advantage if your Scouts know how to orient a map, but anything they need to learn, they can learn at the beginners clinic. Your Scouts should each bring a compass, but they are available for a modest rental fee at the meet. Your Scouts should have good hiking boots, and come prepared as they would for a short hike in the prevailing weather of that day. Waterproof boots will pay for themselves. It is ALWAYS muddier than you expect. Everyone should have their own water bottle, regardless of the weather. I advise my Scouts to bring a light trail snack.

As each meet gets closer, you'll be able to find a pre-registration link on the website. There is a fee for participating, which pretty much just covers the cost of printing the maps. I recommend registering and paying in advance, as this guarantees you the number of pre-printed (control locations printed on them) maps you order. It's also a little cheaper, but if you want to wait until you get there, you can do that too. Payment is by groups. The club recommends no more than 2 in each group, as this maximizes the experience for each person, but of course with BSA Youth Protection guidelines, we usually go with 2-3 Scouts together with 1-2 adults, as the situation dictates. Of course, in these situations, the adults are somewhat duty-bound to just follow, and let the Scouts lead. And yes, it IS hard to let them get lost, but I find it pays off in the long run.

And yes, you may assume that rain or snow will NOT stop an orienteer, just slow them down. I've seen ONE of these meets cancelled in the past 10 years or so, and that was when the wind chill was pushing -50. Can you believe they didn't advertise the cancellation? My Scouts were SO ticked when we go there and found no one else! Rain or snow, though? No problem.

To learn more about the sport and skills of orienteering, Orienteering USA offers a brief primer on orienteering skills and term definitions (e.g., handrails, attack points and distance judgment). The Wood Badge Guide also offers a much more detailed explanation of orienteering skills.