Electricity: A form of energy resulting from the existence of charged particles either statically—as an accumulation of charge or dynamically—as a current. Electricity is measured in watts, and can be calculated using the equation watts = amps x volts, or W = AV. Electricity is stored in batteries statically, but when they are hooked up to the tester, electricity flows through the circuit dynamically as a current. Battery capacity is typically measured in amp hours.

• Watt (W): The SI unit of power. A watt equals one joule per second of energy converted or transferred: 1 W = 1 J/s. Wattage can be calculated using this equation: W = AV.

• Ampere (A): The SI unit of electric current. An amp equals 6.241509074x10¹⁸ electrons worth of charge moving past a fixed point in one second. Amperage can be calculated using this equation: A = W/V.

• Volt (V): The SI unit of electromotive force, the difference of potential that would drive one amp of current against one ohm resistance. A volt equals one joule per coulomb: 1 V = 1 J/C. Voltage can be calculated using these equations: V = IR and V = W/A.

Resistance (R): The degree to which a substance or device opposes the passage of an electric current, causing the dissipation of energy. Resistance is measured in ohms (Ω), and can be calculated using the equation R = V/I. The battery tester contains four resistors. They are connected to different contacts so different batteries' currents will flow through the resistors with the appropriate degree of resistance. The 9V battery contacts connect to two resistors with values of 200Ω of resistance and ±1% tolerance, and 3.60kΩ of resistance and ±1% tolerance. The adjustable contacts for AAA, AA, and D batteries connect to the other two resistors with values of 3.90Ω and ±1% tolerance, and 560Ω and ±1% tolerance.

• Current (I): A flow of electricity that results from the ordered directional movement of electrically charged particles. It is a quantity representing the rate of flow of electric charge. Current is usually measured in amps, and can be calculated using the equation I = V/R.

• Ohm (Ω): The SI unit of electrical resistance, expressing the resistance in a circuit transmitting a current of one ampere when subjected to a potential difference of one volt. An ohm equals one volt per ampere: 1 Ω = 1 V/A. Ohmage (resistance) can be calculated using this equation: R = V/I.

One thing I did well during this project was planning. I planned out when I would complete each component of the project, so I could delegate as much time as possible to sketching the device. I knew I would be able to finish the flowchart and questions in one class period, so I made sure to create a neat, detailed sketch rather than a cursory one in an attempt to finish quickly. I drew my sketch using an orthographic perspective because of the simple nature of my device.

I also managed pressure well during this project. This was our first big project, and we completed it individually. This meant that I was solely responsible for every aspect of it. This was a pretty high pressure situation since I hadn't done a project like this in a while, let alone by myself. But, I managed to plan everything out and stay locked in. I worked diligently and completed everything during the time provided in class.

One thing I struggled with was creativity. I did not manage to bring much creativity to this project, which is unfortunate because that is one of my favorite ways to make work more engaging. I usually do this through my designs, but my sketch was pretty cut and dry. I think this had a lot to do with my device as well: its simple design and lack of overlapping elements made an exploded view sketch seem unnecessary. Hopefully, in the future, I can work harder on my sketches, maybe even working on them after school if I have to.

I also struggled with my attention to detail. Since the design of my device is pretty simple I should have used that as an opportunity to really focus on the individual components more. I should have labelled the resistors with their appropriate ohm (Ω) value in my sketch. I think the reason I neglected to do this was because we finished our designs before conducting research, and I really did not remember much about resistors. I could have also drawn the front of the display. The display is just a simple analog dial, but, again, it would have added to my sketch if I focused more on the individual components. In the future, I will try to pay more attention to detail and may even make mini separate sketches for individual parts or subsystems of a device if warranted.