2) On Saturday, follow Wanda MacLachlan of the University of Maryland Extension Service for a walk in the woods to learn to identify native trees. The free program, being offered by the Howard County Conservancy, begins at 10 a.m. MacLachlan will teach participants how to use a decoder key (which they get to take home) to assist them. If it's raining, the entire thing will be held under cover. The program will be at the Conservancy's Mount Pleasant Farm on Old Frederick Road between Bethany Lane and Woodstock Road. Questions? Call 410-465-8877.

3) Join the Sierra Club Saturday on a 7-mile hike in the Hilton area of Patapsco Valley State Park. It's a moderate jaunt that will take you through some pretty scenery at the state's oldest park. Meet at 9:15 a.m. in the parking lot behind the nature center, just on the right inside the Hilton Avenue entrance. Bring water and lunch. If you need to flesh this one out, call hike leader James Perschy, 410-964-1902 or shoot him an email, jameshike@verizon.net.

4) If the skies cooperate on Saturday evening, watch the Perseids meteor shower at Soldiers Delight Natural Environment Area with members of the Westminster Astronomy Club, from 8 p.m. to 10 p.m. If cloud cover obscures the light show, the club will talk about the rocks that fall from space. The program is free, but donations are welcomed. Need more? Call 877-794-0606.

5) On Sunday, which is expected to be on the damp side, take a walk the way a raindrop would travel at Harford County's Anita C. Leight Estuary Center. You'll take a walk in the woods as well as spalsh through Otter Creek on this 90-minute detective exercise, which begins at 3 p.m. This is suitable for anyone older than 5. The cost is $2 per person. Give the center a shout at 410-612-1688 to let the staff know you're coming.