1. Clean it up? Or let it grow? Take the Earth Day Challenge at multiple natural settings:
Reinstein Woods Nature Preserve, 93 Honorine Drive, Depew -- noon to 4 p.m. Saturday: Tour the woods, hunt for scavengers and drink organic refreshments while you save energy in the "green" education center. Free.
Tifft Nature Preserve, 1200 Fuhrmann Blvd. -- 2 to 5 p.m. Sunday: Highlights include recycling and backyard composting workshops, bird and bat houses, preserve tours, puppet theater, a white spruce seedling giveaway, live music and a raffle. Cost $5.
Aquarium of Niagara, 701 Whirlpool St., Niagara Falls -- 9 a.m. to 5 p.m. Sunday: First 200 families receive a Douglas Fir seedling. Cost $8 adults, $5.50 children.
2. Make sure to follow your earthly activity with a peek at the stars Monday at Williamsville North High School, 1595 Hopkins Road, Amherst.
View Mars, Orion's Nebula, Sirius, the winter triangle and Beehive Cluster M44.
Presented by the Hamburg Natural History Society and the Williamsville Space-Lab Planetarium for free. Program begins at 6 p.m., with planetarium shows at 6:30 and 7:30. Call 627-4560 for details.
3. Electric Avenue in Lackawanna lives up to its name Monday with a free concert by the Canisius College Chorale inside St. Michael the Archangel Church. Featured will be works of Mozart, Buxtehude, Beethoven, Croce and Diemer.
Show starts at 7:30 p.m. Find it at 144 Warsaw St. (at Electric).
4. Get thee to North Tonawanda and mark 150 years of history from 1 to 5 p.m. Saturday in the ballroom of the Benevolent and Protective Order of Elks Lodge No. 860, 21 Main St. Tour the lodge, eat cake and drink in the atmosphere.