Teacher Notes - DOC

							Name _____________________________________ Due Date _____________ Class ___________

Challenge Assignment
Cause for Alarm
Most drivers rely on lights, buzzers, and bells to tell
them when the fuel or oil is low, the temperature is too
high, or the seat belts are not fastened. These lights,
buzzers, and bells are examples of alarm circuits.
Building an alarm circuit is just a matter of causing a
switch to close so that there is electrical current through
a light or buzzer. The example at the right shows a cross-
sectional view of a circuit that will turn on a warning
buzzer when somebody attempts to take the cookie
from the counter. Lifting the cookie will cause the metal
washer to connect the two pieces of aluminum foil.

Your Task: Build an alarm circuit that turns on a light when it detects some event that you choose.

Project Materials Needed:
 You will need one 1.5-volt dry cell (flashlight battery), about 3 meters of insulated wire, and a
   light bulb supplied by your teacher.
 You will also find it helpful to gather various metal materials to use as part of your switch. These
   might include aluminum foil or pans, paper clips, screws, washers, nails, metal cans, electrical
   tape, soda cans, lemon juice, a basin or bowl, water, or salt.
 You will need sturdy tape like electrical tape or duct tape to hold electrical connections together.

Project Steps:

1. Brainstorm alarm triggers – On a separate sheet of paper, make of a list of events that you could
   use to trigger your alarm. Think of problems you have experienced that an alarm would help you
   solve. To get some ideas, think about ways in which you could detect each of the events
   described below. Think of these as “alarm triggers”:
    Water reaches the maximum level in a container.
    A door or lid opens or closes.
    A window fan set on its lowest setting and placed three meters away blows on your device.
    The attempted theft of a “precious” object. Make sure that you make your alarm tamper-
       proof, because you wouldn’t want the thief to be able to cut any of your wires and disarm it!

2. Design Planning - On a separate sheet of paper, use complete sentences to answer the following
   questions about the switch and circuit that you intend to build.
    What event have you chosen that will close your circuit and trigger your alarm?
    Why did you choose to make this alarm? What problem can it help you solve?
    Make a detailed sketch of your alarm circuit. Label the parts. (Will any parts of your circuit
      hidden from view? If so, make a sketch of these hidden parts, also.)
    List the materials that you will need for building your circuit.
Name _____________________________________ Due Date _____________ Class ___________


3. Building the Circuit - Build your alarm switch and connect it to the battery and light bulb with
   insulated wire to make a complete circuit. When your alarm switch is operated, it should turn
   on/off the light bulb. Make your electrical connections temporary since you will make changes as
   you test and revise your alarm circuit. Keep in mind that you will eventually need to transport
   your alarm circuit to school, so you cannot connect it to your bedroom door or Xbox console!

4. Testing and Revising - Test! Test! Test! Test your device, and make revisions or adjustments.
   Make sure your device works reliably so that you can feel confident that it will work when you
   demonstrate it to the class. Create a table like the one below that you can use when you test and
   revise your circuit.

                            Cause for Alarm – Testing and Revision Table
                  Test #   Problems Encountered           Revisions Made to Circuit
              1
              2
              (More….)

5. Fine tune your product - Once you have successfully produced your alarm switch and circuit,
   improve both the durability and appearance of your design. Indicate all changes on your Testing
   and Revision Table. Some suggestions include: (1) twisting wires together before taping them; (2)
   where bare wire must make contact with screws, cans, pennies, or other pieces of metal, you can
   improve the connection by scraping the insulation from 2.5 cm of wire, wrapping it around the
   object, and covering the connection with a strong tape such as electrical tape or duct tape; (3)
   attaching parts to a board or to the inside of a container so pieces don’t flop around and so the
   device can be carried as a single unit rather than as a bunch of parts.

6. Analyze – Use complete sentences to answer these analysis questions on a separate sheet of
   paper. When they have been completed, you are ready to put together your presentation.
    Write a paragraph to summarize what your alarm switch does/how it functions.
    What difficulties did you have in building your circuit? Explain how you overcame the
      difficulties.
    Describe at least one practical application of how your circuit would be useful in real life.

7. Present – On the due date, you will be asked to demonstrate and explain how your alarm circuit
   works. You will need to submit your completed alarm switch and circuit (Step 3) along with the
   following items stapled together (with your name on each item):
    Brainstorm List (Step 1)
    Design Plan (Step 2)
    Testing and Revision Table (Steps 4-5)
    Analysis (Step 6)
Name _____________________________________ Due Date _____________ Class ___________

Challenge Assignment
Cause for Alarm                                                             Score = _____/20
                                      Assignment Scoring Guide

Scores:      4 = Excellent    3 = Good/fair    2 = Poor/Needs improvement         1 = Unsatisfactory

          Category                                         Criteria                                Score
                         Brainstorm list and design planning is thorough, with detailed
Brainstorming, Planning
                         explanation of the purpose, sketches, and materials list. Student
and Building the Circuit
                         follows all project steps.
Alarm Switch and Circuit Circuit design is very creative; it meets its purpose and works
Design                   correctly every time.
Durability and
                             Product is very durable and shows quality workmanship
Appearance
Circuit Testing and          Testing and Revision Table shows extensive testing was
Revision                     performed that lead to significant revisions to the circuit.
                             Thorough and well-organized. Very detailed
Analysis                     description/explanation of alarm’s function, difficulties
                             encountered and solved, and practical application.
Name _____________________________________ Due Date _____________ Class ___________

Teacher Notes

Challenge Assignment
Cause for Alarm
Skills Focus: Applying concepts, designing a solution, evaluating the design, redesigning,
communicating

The following steps will walk you through the Chapter Project. Use the hints and detailed directions
as you guide your students through design, test phase, and presentation.

Chapter Project Overview
In this project, students will work individually or in small groups to construct an alarm circuit that will
light a bulb in response to an event of their choosing.

To introduce the project, construct a “Penny Detector” to show students how contact between the
ends of two wires can turn on a light. Tape an uninsulated end of a piece of wire to a penny. Connect
the other end of the wire to a light bulb. Connect the light bulb to a dry cell. Tape the other pole of
the dry cell to an empty metal can. Dropping the penny into the can will turn the light on.

Have students read the Chapter Project Overview. Review the project’s rules and hand out the
Chapter Scoring Rubric you will use for scoring students’ work. Discuss with students what will be
expected of them.

Have students brainstorm a list of detectors, triggers, and alarms they see in their everyday lives.
Indicator lights in cars, thermostats, fire and smoke alarms, car and home burglar alarms, and lights
that turn on automatically at sunset are a few examples of what are actually switches in an electrical
circuit.

If students are having a hard time designing their detector switches, help them along by providing
hints as to how they might get the two ends of the wires to come in electrical contact with each
other. For example, they might connect a wire to a ping pong ball wrapped with aluminum foil,
floating in a container of water that is lined with aluminum foil. As water drains out of a hole in the
bottom of the container, the ball will come in contact with the liner, completing the circuit.



Materials and Preparation
Each student will need one or 1.5-volt battery, about 3 meters of insulated wire, and a light bulb.
Make sure to select bulbs that require only 1.5 volts from a single battery. Additionally, students may
need aluminum foil, paper clips, screws, washers, nails, metal cans, electrical tape, basins or bowls,
water, or salt.
Name _____________________________________ Due Date _____________ Class ___________

If holders and sockets for the dry cells and bulbs are not provided, alligator clips will make it easier for
connections to be made. You may need screwdrivers for securing connections to the various
components.

Keep Students on Track— Day 1
Help students understand that a switch does not have to be a ready-made device like those we find
on the walls for homes or the front panels of our stereos. A switch is simply a device that allows
current where it could not exist before. Have students to brainstorm events that cause a light,
buzzer, or machine to automatically turn on. Their lists might include indicator lights in cars, the light
in a refrigerator, alarms in stores and libraries that prevent theft, etc.

Keep Students on Track— Day 2
Encourage students to begin working on their circuit design. They should also make a list of materials
they will need for constructing their circuit.

Keep Students on Track— Day 3
Make sure students conduct several tests of their circuit. If their circuit fails to function properly, they
should modify their design. If students are having difficulties getting started with their design, you
may want to make some suggestions of possible ideas. You may also want to give some hints as to
how students might get the two ends of the wires to come in electrical contact with each other.

Keep Students on Track— Day 4
Students should have completed initial tests of their circuits and begun redesigning to find solutions
to any problems. Help students analyze their circuits, and make suggestions that will improve the
completion of the circuit when the event occurs. Encourage students whose designs function fairly
well to look for ways to improve both the design for more efficient function.

Keep Students on Track— Day 5
Check that all students have completed testing their alarm circuits and finished their redesigns. Help
those students having difficulty by suggesting ways in which they can improve their designs to make
the alarm circuit function as planned.

Due Day
Many students will need to make final connections and adjustments when they set up their projects.
Have students turn in any written work you require, such as the one-page description, circuit
diagram, and, if appropriate, the drawing of hidden parts.

Extension
Have all students design burglar alarms. As you test these alarms, pose as a burglar, doing your best
to disarm the alarm before stealing the “precious” object. Tell students at the beginning of the
project that you will be attempting to snip exposed wires and do anything else you can so that you
don’t set off the alarm. Students will enjoy the extra challenge of trying to make their alarms
foolproof.