By the end of this lesson, each pairing of students, under the guidance of an adult, should have constructed a working radio. In order to do this, it will be necessary for them to develop a correct and efficient soldering technique. Each student pairing should also be able to identify the circuit components used to construct their radio, as well as explain how their radio is functioning.

• Students' interest can be sparked by explaining to them that many college students complete similar projects in their electrical engineering classes—yet they are conducting a similar activity in middle school or high school!
• It is likely, however, that explaining the goal of this activity (to solder components to a circuit board to create a working AM radio) will be enough to spark the students' interest.

Before the lesson:

• Before the lesson, it is helpful for the teacher to build a radio with the kit themselves. The diagram for the placement of circuit components can be confusing at times, so this will ensure that the teacher fully understands the schematic before introducing it to the students, as they will invariably need assistance.
• As students will need guidance for this, especially at younger ages, it is very helpful to have more adult supervision available to ensure that the soldering is done safely and correctly. It is best if desoldering can be kept at a minimum, so more adult supervision will ensure that the students are placing the circuit components in the correct place before they are soldered to the circuit board.
• Stations for each student pair should be set up with the following items: a radio kit, wire clippers, a soldering iron with a wet sponge to wipe the tip of the iron if solder gets on it (comes with the soldering iron), solder, goggles.
• When practicing the soldering, each station should also have a practice breadboard and about 20 resistors.

With the students:

• The students should first be given an introduction to soldering. A good explanation of how to solder is found at http://www.aaroncake.net/electronics/solder.htm. First explain to the students that the components should be inserted into the side of the breadboard which is plastic and has no metal, thus, the leads stick out the metal side. The board should be flipped over to the metal side. The solder should be held at the base of where the lead emerges from the hole in the breadboard. The soldering iron should be placed on the lead as well, but at a position slightly above the solder, so that it is close, but not touching. When the tip of the soldering iron touches the solder, the solder melts, covering the tip; repetition of this occurrence can ruin the tip. If solder gets on the tip, have the students clean off the tip with the wet sponge located on the soldering iron docking station.
• As the iron is held just above the solder, the heat from the iron makes the solder melt around the base of the lead. Enough solder should be melted such that the entire base is covered, making a small "mound" of solder at the base of the lead. When practicing, the students should experiment with using different amounts of solder so they can identify the correct amount to use; this entails finding the balance between using enough solder to create a good connection, yet not so much that the entire breadboard is one large network of solder. Once the base is covered, soldering should follow the "less is more" rule. After soldering is complete, the excess lead wire is cut with the wire clippers provided at each station.
• It is also important to explain soldering safety to the students. Goggles should be provided at each station and worn by the students to prevent any eye injuries. Explain that the soldering iron is very hot and that the metal on the back of the circuit board conducts this heat, so they should be very careful when touching any metal pieces that have the potential to be hot. This is especially true for the soldering iron itself. Often one student will hold a component in place or hold the solder, while another holds the iron; each student should pay careful attention to where the soldering iron is with respect to the placement of each group member's hands. The potential for a student to get burnt is very high, so warning them against any misuse of the iron may help reduce the incidence of injury.
• Once soldering has been both explained and demonstrated to the students, each group should be equipped with a practice breadboard and several resistors. The students should practice for at least 45 minutes and show samples of their final soldering technique to the teacher before moving onto their actual radio kit.
• Upon opening the kit, each part should be identified and found on the list of parts located on the instructions for building the radio. Matching the parts to this list will help when placing each component on the circuit board, because they will also be matched to the label the kit instructions give the component. The diagram showing where to place each component uses these labels, so matching the component to its corresponding label will ensure that the component is placed correctly on the circuit board.
• Once all of the components have been sorted, recommend that the students begin soldering the resistors first. It is easiest to build the radio using the flatter components first and then adding the taller or more complex components towards the end. Also, resistors are less heat sensitive, so if students are still taking a while to solder each component, it will not ruin the resistors like it may ruin other components. Thus, the students will identify the resistor of the correct value (using the color bands) and solder it to the proper place on the circuit board using the kit's diagram. Once the resistors have been added, the diodes are the next likely circuit component to add. It is important to note which direction the diode should be oriented, as a diode facing the wrong way will cause the radio to malfunction; the black band on the diode specifies the positive side. Next the capacitors should be added, followed by the inductors and any other components requiring soldering. The speaker should be attached last and will require using the wire specified in the materials section.
• Be sure to consistently check on the groups to make sure the components are being soldered in the correct position to prevent having to debug the radio later by desoldering components.
• Also warn students that most of the components are heat sensitive, so the soldering iron should be placed on the lead of the component for a minimal amount of time.
• Once all of the components have been soldered to the circuit board, a 9V battery should be used to power the radio. Find a radio station by tuning the signal slowly; the volume should be at its maximum setting. It may be difficult to find a signal in a certain area, so conduct further investigation into tuner adjustment and antennae orientation before trying to debug the radio. If the radio still does not work, check all of the soldered components to ensure that they are both soldered correctly and in the right place. A previously completed radio allows for quick checking.

If a radio does not work, ask the following questions:

• Are resistors of the correct value placed in the proper place?
• Are the diodes in the proper orientation (positive side corresponding to black band)?
• Are all of the soldering connections complete? i.e. is the entire hole the leads emerge from covered?
• Has the wire connecting the speaker or 9V battery to the circuit board been stripped enough?
• As the diodes, transistors and integrated circuit are very heat sensitive, have these parts been overheated?
• Additional troubleshooting tips are included in the kit directions

Pre-activity assessment:

• Resistor Value Worksheet from Circuits Lesson
• Correctly identify circuit components
• Explain concepts of AM radio signal transmission

Activity embedded assessment:

• Correctly read the diagram found in the kit directions, as well as match the corresponding component to its symbol on the diagram.

Post-activity assessment:

• Check if the radio works
• Ask students to generally explain how their radio is working

• The level of adult involvement will affect the scaling a great deal; the more involved adults are in the completion of the radio, the less time it will take. While adult involvement will conserve time, however, it will also impede student's full understanding of how the radio is functioning.
• The activity can be made more difficult as the depth of material concerning how the radio signal is interpreted by the radio increases