Learning Aims: Understanding what is the purpose of batteries in series and how the series connection of batteries influences its characteristics Understanding what is the purpose of batteries in parallel and how the parallel connection of batteries influences its characteristics Materials: Two (or more) batteries (e.g. 4,5V zinc-carbon battery), leads, resistor with adjustable resistance (e.g. 100), computer, interface and software (e.g. CMA Coach6), current sensor, voltage sensor (if computer with interface is not available, ammeter and voltmeter can be used) Suggestions for use: In this activity students investigate the behaviour of batteries connected in series and in parallel in order to find out the purpose of these connections. They should be already familiar with the battery characteristics in terms of emf and internal resistance as well as with the series and parallel connection of resistors. Divide the class into small groups of 2-3 and hand out Classroom Material: Battery in series and in parallel. The activity can be carried out in a bounded inquiry mode. They can investigate the connection of identical or different batteries. Students plan the experimental procedure on their own and draw conclusions about the emf and internal resistance of a battery that is equivalent to series or parallel connections. They can investigate the power supplied to the load. Linear fits to terminal voltage vs. current allow students to extract values for emf and internal resistance and compare the calculated maximum power and the load resistance at which it occurs with the experimental data. Possible Questions: How does the emf and internal resistance change if batteries are connected in series (parallel)? Discuss the connection of two identical and two different batteries. How to connect two batteries for maximum power transfer to the load?