Parallel Circuits Day 2

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Objective

Students will be able to create a parallel circuit using prior knowledge about the flow of electricity.

Big Idea

Students have been building series circuits all along, without it being defined as such. They now have enough working information to define series and parallel circuits and build both.

Question

5 minutes

Students worked yesterday to investigate ways to build a circuit that ran off of one source and powered two receivers to their full capacity. This was a challenge, as they were use to working with series circuits. 

However, after a session of exploring and trial and error, they are ready to build parallel circuits and answer the question "How can you use one source to power two receivers at their full capacity every time the circuit is closed?"

Mini Lesson

5 minutes

As a mini lesson today, I reminded students that a series circuit is a is a closed circuit in which the current follows one path.  

Yesterday, I did not give the students the definition of  a parallel circuit. I was saving that for right now. I wanted the students to explore and make sense of the situation before defining anything for them. However, now I explain that there are circuits, called parallel circuits, in which the current can follow more than one path. 

Next, I ask the students to draw, on their whiteboards, a schematic that might be a solution to the problem of having only one source of energy and two receivers that need to be working in full force. 

As they share their ideas, I asked them to look around for similarities and differences. This is a wonderful way to get their minds revved up for the activity. 

Active Engagement

20 minutes

As the students work, I usually begin circulating right away.  Today I waited for them to build their circuits and requested them to send a representative to me in order to "observe" their work. Then, when I approach, I am able to ask the students to defend their work and prompt them to delve into their understanding further. 

 When these students approached me with a "We got it!" message, I sat down with them.  It was obvious to me that they had a series circuit, but thought it was a parallel.  I needed to review with them in a way that made sense to them (tracing the path) and then give them an idea of how to go about revising their model. 

When the girls began to revise their model, I then guided them in their thinking until they were ready to draw their schematic. 

This team was ready to share with me and I was impressed that their circuit was so simple, yet correct. They really understood that they did not need all of the components available on the supply table.  I was then able to discuss with them "why" they made the design decisions that they did. This is a much more rigorous conversation. I am sorry that my sound was muffled at the end of the discussion by my hand, but the boy was explaining that if there were two sources, then each receiver would essentially be in its own circuit and they would become series circuits. 

This team used a switch in one of the pathways.  I decided to use this as a questioning prompt.  You will hear the students discussing, using precise vocabulary, why their design works. However, as we moved into the discussion of the switch, which really controls just one bulb, I realized the students had a misconception. I do not correct them here, however, as I will use it in my lesson tomorrow. By the way, don't you love the expression "electricians" for electrons?!

Closing

5 minutes

To close, I asked the students to draw a schematic of their working parallel circuit. I will use these in a future lesson to begin the discussion of various solutions to one problem. 

This is also a great exit ticket exercise, which will quickly create accountability for the students in expressing their learning and understanding.