Yesterday, I took a class on soldering at Tech Shop. For the first 30 minutes, the instructor explained the characteristics of soldering, such as the different types of solder. Lead solder is stronger and shinier than lead-free solder. However, lead solder is considered to be toxic because it is half lead, half tin. Since lead solder is toxic, it also has to be dropped off at a recycle facility or it can contaminate the landfill and get into the groundwater. Nowadays, most people use lead-free solder which is made out of tin, copper, silver, and traces of other metals.
For our first project, we put together a person out of 4 paperclips. You can find instructions on instructables.com on how to make your own (with a soldering iron) here. For our second project we built a simple circuit based on a RGB LED that would let one light up different colors based on which combination of buttons was pressed. (Fun fact: In a regular LED, the longer lead is usually positive but in a RGB LED the longer lead is negative. )