Have students discuss what they know about light and research the basic components of light. You may watch the following video on introduction to light- its types and properties.

https://www.youtube.com/watch?v=CIWEJEYD-bg

Show and define resistors and talk about what they are used for. You may watch the following introductory video on resistors and also find more information at www.resistorguide.com.

https://www.youtube.com/watch?v=Gc1wVdbVI0E&t=139s

Research Ohm’s Law (1827) and learn about the German scientist.

Essential Questions: What are the main components of light and what is a resistor used for?

1. In a whole class session, students will learn the components needed to correctly solder and wire an LED bulb to light up using a resistor to prevent from blowing the bulb.
2. Define the following key concepts:
3. Sources of Light: Natural light such as the sun, moon, lightning, etc. versus artificial light such as flashlights, candles, light fixtures, etc.
4. EMR: Electromagnetic Radiation; a kind of radiation including visible light, radio waves, gamma rays, and X-rays, in which electric and magnetic fields vary simultaneously.
5. Wavelength: the distance between successive crests of a wave, especially points in a sound wave or electromagnetic wave.
6. Frequency: the number of occurrences of a repeating event per unit of time.
7. Resistor: a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active elements, and terminate transmission lines, among other uses.

Formative Assessment: Students should understand the general make-up of light and how it is produced. They should be able to define the purpose of a resistor and when or why it would be needed.

Essential Question: How can you determine the type of resistor needed for your flashlight based upon the voltage produced and the type of bulb being used.

1.  Visit www.resistorguide.com to learn more about the fundamentals of resistors, the types, and applications of resistors.

Formative Assessment: To show that students have a basic understanding of resistors and are ready to begin soldering the electronic components, ask questions to have students demonstrate their understanding and knowledge of the definition, types, and applications of resistors.

 2. Solder the internal components of the flashlight (battery holder, resistor, LED bulb, tactile switch)

• Depending on the type of case designed by the student to hold the internal components of the flashlight, wires can be cut and tactile switch can be placed wherever necessary to accommodate the case. The attached pictures can be used as a general guide of how we completed our flashlights.
• Solder the red (+) wire from the battery holder to the positive (longer prong) of the LED bulb. We cut this prong shorter to accommodate for the size of the case we designed.
• Solder the resistor to the negative prong (shorter prong) of the LED bulb. We also cut this prong shorter to fit into our case.
• Solder the black (-) wire from the battery holder to the resistor that was previously soldered to the negative prong on the LED bulb.
• Cut the black wire from the battery holder near the middle to insert the tactile switch. Note: when soldering the tactile switch to both sides of the black (-) wire, make sure to solder to diagonal prongs on the tactile switch or you will get a constant “on”. This can lead to more discussion about tactile switches.
• Insert A23 battery and press tactile switch to make sure everything is functioning correctly and the LED bulb lights up.