To achieve the second Milestone, students begin to investigate the function of different components in a circuit. For example, to examine the role of the battery, students experiment with electron transfer between metals, build cells with different pairs of metals, and measure how voltage varies with different batteries over time. Milestone Two presents a motivating opportunity for consolidation, application, and assessment. Students establish criteria for choosing the most appropriate battery for their defibrillator model weighing variables such as voltage, cost, and rate of discharge. They choose a battery and justify their choice.
Students move on to investigate how current varies with changes to voltage or resistance.
While looking for patterns in the data, they attempt to form an algebraic equation that represents the relationship between voltage, current, and resistance. Determine a scale for your defibrillator that is safe to experiment with and determine the associated voltage output. Design a first version of the schematic diagram of your circuit and build a rough model of the circuit. As you re working, identify questions the answers to which will help you improve your design. Students then address questions emerging from their first try.