Iowans who are looking for something unusual to do this weekend might consider a free class on how to make maple syrup. All you need is a maple or box elder tree in the yard, a few basic tools and a little time. Christine Kirpes , a naturalist at the Indian Creek Nature Center in Cedar Rapids, says the conditions are perfect. Kirpes says when it’s still freezing at night but temperatures rise into the 40s and 50s during the day, the sap starts to flow and can be tapped. She says the process of tapping a tree isn’t complicated, but you have to follow a few basic rules, like only choosing a maple or box elder that’s at least ten inches in diameter. Drill a hole in the trunk one-to-one-and-a-half inches deep, insert the metal spout and collect the sap. It has to be boiled down, which can take a long time.She says the sap is 98-percent water and two-percent sugar, so it takes many, many gallons of sap to make just one gallon of syrup. The free syrup-making workshop starts at 10 A.M. For more information, call the nature center at (319) 362-0664.