Introduction: Wiring a Doll House: an Electricity Unit Final Task
If you teach about series and parallel circuits, resistors, current, or voltage, than this may be the project you are looking for!
This was developed as a final summative assessment for a grade 11 physics class in British Columbia, Canada, though you can easily modify to meet the needs of your classroom or grade level. I hope to explain how I use this hands-on collaborative project in my class and maybe you will trying something similar in yours!
The overall idea is to use LEDs and copper tape to light up the inside of a doll house. In this iteration, I provided specific functionality expectations (in the documents below), but next year I plan to have the students decide what they need to accomplish to demonstrate their learning.
Students work in groups (I prefer a max of 3) and each group will need the following:
- Doll house (I use this one from IKEA)
- Copper tape roll (Amazon)
- Five different colour LEDs (Amazon)
- Power supply or 9V battery
- Pair of wires with alligator clips
- Four SPDT switches (Amazon)
- 10KOhm Potentiometer (Amazon)
- Access to resistors of all sizes
Step 1: Step 1: Student Handout & Rubric
Below you will find editable versions of the handouts I provided students. One indicates the expectations and materials, and the other is the rubric I used. Briefly, the expectations are:
- Each room has its own switch and at least one LED
- One room should be dimmable
- The large upper area should have 2 switches that both control the lights
To this point in the course, students have generally only worked with non-LED bulbs in other activities. This is intentional so that students have to use their knowledge of Ohm's Law and current flow to determine the correct resistor. This link is provided for reference, but still requires them to understand what they are reading and use it: Resistors for LEDs.
As well, students have not used potentiometers either. This link is provided to help them get started, but it often is only a starting point in their research to understand how to wire it: What is a Potentiometer?
For assessment, students submit a report individually with the following minimum expectations:
- Circuit diagram
- Reasoning for use of series and/or parallel
- Resistor calculations and explanations
- Safety check to ensure resistors are below power rating
- Calculation of overall current
The rubric is set up in the spirit of Standards Based Grading, though it is not using course standards (I am still developing those). Use it as you would any other rubric.
Important Note: I do not provide a timeline or due date for this project until students are nearly complete. The amount of time it takes students varies greatly, so I always ensure everyone has the time needed to succeed. If a group finishes dramatically early (not common), you can challenge them to add something electrical that a younger child might want in a doll house.
Step 2: Step 2: Student Work Time
The photos throughout the Instructable are of student work to give an idea of what the finished product could look like. During class time, I visit each group to understand their progress and current challenges. Sometimes, if a challenge persists, I will provoke them without giving out answers.
Problem solving is a large part of this project, such as the copper tape being finicky. As a result, I often help students use the equipment to learn more about iterative testing. Initially many students see only the whole project and test it as a whole. With support, I show them how to use their equipment to isolate issues and decompose the problem so it feels more manageable. As an example of this, consider the scenario below:
A group has lights working in one room but not another. Students can move the power supply to isolate the non-working room, and continue to move it around to identify a possible loose connection. They also have to think critically about the power supply voltage to ensure an LED doesn't burn out if they bypass a resistor (which happens often).
Another major problem is creating a 3-way switch system, which I set as an expectation. This pushes them to think deeper about current flow, and also why you need to use SPDT switches. I try to avoid helping with this particular problem and allowing the collaboration between groups to spread the information (someone always figures it out eventually).
Truthfully, the skills developed throughout this task are likely more valuable then the specific circuit knowledge for many of the students.
Step 3: Step 3: Final Thoughts and Next Steps
I have used this project for two years now and it is often a student highlight of the year. After the first year, I added wire extensions to the switches and potentiometers to make it easier to connect with the copper tape. Other than the copper tape, all of the materials are reusable each year but the houses do take up a lot of space.
I do have a few changes that I am considering implementing for next year.
First, I want to transfer the development of the expectations to the students. For example, leading a discussion with them to identify what types of lighting requirements a doll house might need. This is also a more authentic way to discuss relevant safety precautions they should consider, like the power ratings of resistors.
Secondly, I want to build in a self-assessment component focused around problem solving and critical thinking. Reflection is a vital component of the learning process, and it is important for students to have the time to reflect on a major task like this one.
As a reminder, this activity is meant to challenge students to apply their knowledge of circuits in a hands-on authentic way. It has worked well so far, so I figured I should share it but I will continue to develop my use of this project. If you have any ideas or questions, let me know!