Build a Battery
GK-12 Fellow : Michael Nolan
GK-12 Teacher: Jacqueline Stew art
Date of Lesson: November 2014
Grade Level:
_ 7 t h Grade
Content Area & Topic:
__
Agriculture
__
Animals
__
Astronomy
__
Cells
_X_ Other: Energy
X 8 t h Grade
_X_
__
__
__
_ 9 t h -12 t h Grade
Chemistry
Engineering
Environment
Genetics
__
__
__
Health
Physics
Plants
Lesson Overview:
Students will build a classic voltaic pile battery to power an LED light. Given the relatively low cost of
materials, students may take these home. The activity will illustrate energy conversions and introduce
the concept of electric currents. If powering something other than LEDs, the activity can also be used
to teach about batteries in series or parallel.
Length of Lesson:
40 minutes
Iow a Core Statement (See Content Map for your grade level on intranet):
Understand and apply knowledge of forms of energy and energy transfer
I can recognize examples of energy conversions in real situations
Content Objectives (SEE Content m ap for guidelines):

Forms of energy

Energy conversions
Materials:
For the class:
1 or more multimeters to measure voltage/current
D e ve l o p e d b y: S ym b i , I o w a S t a t e ’ s G K - 1 2 P r o g r a m wi t h t h e N a t i o n a l S c i e n c e F o u n d a t i o n
E n g i n e e r i n g R e s e a r c h C e n t e r f o r B i o r e n e w a b l e C h e m i c a l s ( C B i R C ) a t I o w a S t a t e U n i ve r s i t y
W eb s i t e : www.gk12.iastate.edu E m a i l : symbi@iastate.edu
Per student:
8” to 12” electrical tape
4 half-inch squares of matboard or cardboard
4 post-1982 pennies (pre-1982 pennies also work, but it is better to save them for other purposes)
4 3/4” galvanized washers (nearly identical size to pennies)
~5 ml vinegar (a large bowl of vinegar 1” deep is fine for ~100 students)
For the tape and matboard/cardboard, it may be easiest to have students cut these themselves.
Lesson Procedures:
***** Before the activity
For cost considerations, it is a good idea to start shopping around for LED lights early, preferably a
month early, as it is good to order a few LEDs and try them. The kind you are looking for are called
“through-hole LEDs.” It is possible to find LED lights that are 20 cents or less each, compared to the
rest of the battery, which costs about 14 cents for a 4-cell battery. Finally, the cost of the battery can
be cut by 3 cents by using a 3-cell battery, if that is sufficient to power the LED. The cheapest setup I
found so far was a 4 cent LED from electron.com, combined with a 3-cell battery, making a total of 15
cents per “flashlight.”
***** Common pitfalls
There is an unlikely possibility of a low-voltage LED being so low voltage that it “pops” upon
connection to the battery, rendering it worthless. A more likely and equally frustrating outcome is if the
LED requires more power than the battery can deliver. Before giving up on a non-working LED,
though, make sure that you have tried touching the leads in both directions. LEDs are directional,
meaning they only work if the right lead is touching the right side of the battery (this is because
electricity only flows one direction in an LED). When we made this, touching the long end to copper
and the short end to zinc worked, though it is always possible that the long and short ends are
reversed in your case.
After the LED, the battery must be constructed properly. Since we are working with vinegar, you must
be careful that the cardboard/matboard is not too wet, otherwise vinegar dripping out will short the
battery and prevent it from working. After the vinegar, another common error observed was to put
wetted matboard between cells, which also shorts the battery. Follow the directions and make sure
that there is metal-to-metal contact between cells.
***** Activity
Set up table groups of 4 (give or take depending on your classroom) with just the right amount of
pennies and washers in the center of each table. Also include the matboard/cardboard, tape, and
scissors, and have the vinegar in a bowl. Instruct the students to cut the cardboard/matboard and
place their squares into the vinegar. Lead the class through constructing a single cell:
Penny
Wetted cardboard/matboard
Zinc washer
D e ve l o p e d b y: S ym b i , I o w a S t a t e ’ s G K - 1 2 P r o g r a m wi t h t h e N a t i o n a l S c i e n c e F o u n d a t i o n
E n g i n e e r i n g R e s e a r c h C e n t e r f o r B i o r e n e w a b l e C h e m i c a l s ( C B i R C ) a t I o w a S t a t e U n i ve r s i t y
W eb s i t e : www.gk12.iastate.edu E m a i l : symbi@iastate.edu
After having the class build a cell, instruct the students to build four cells. Once these are built, stack
them one on top of the other so the layers look like this:
Cell #1 >>
penny
matboard
washer
penny
matboard
washer
Note that there is no matboard between the cells! Now, have students bend the leads on the LED so
that they can touch the long end to the copper at the very top and the short end to the washer at the
very bottom. Assuming the batteries were built correctly, they should light up. Finally, have students
use the electrical tape to tape around, over, and under the battery to seal it up as tightly as possible.
The students may take these home.
***** Math connection
If you have a multimeter, it is possible to lead the class in a discussion about measuring the voltage
across each cell, and seeing how adding more cells in series (stacking them on top of each other)
changes the voltage. Typically each cell produces 0.5-0.7 volts, so you tend to get a nice linear
relationship when stacking the cells, which can then be plotted.
Once you have a plot to show the effect of stacking cells, you can then try to change the battery
construction to see how the relationship changes. For example, instead of using vinegar one can use
salt water or lemon juice, or using two pieces of matboard/cardboard instead of just one. Also, the
materials can be changed. One can try, for example, a penny-nickel battery, a penny-steel battery
(find stainless steel washers instead of galvanized), or any combination of small metal discs. The
same linear relationship should show up, but the slope of the line should change. Since the LEDs
require a minimum voltage, have students use the linear relationship for each battery type to calculate
the number of cells they need.
The reasoning for the linear relationship should be obvious; each cell has a voltage, putting them
together adds the voltages together. However, the voltage per cell changes when the battery
construction is changed, either because 1) the battery cell is less able to move charges across the
wetted layer, or 2) the electrochemical reaction between the two metals has an intrinsic voltage, and
the battery cannot go above that voltage. The electrochemistry involved in batteries is beyond the
scope of an 8th grade course, but the question may come up.
Evaluation/ Assessment:
There is a worksheet that goes with the activity.
References:
Biorenew able Connection:
D e ve l o p e d b y: S ym b i , I o w a S t a t e ’ s G K - 1 2 P r o g r a m wi t h t h e N a t i o n a l S c i e n c e F o u n d a t i o n
E n g i n e e r i n g R e s e a r c h C e n t e r f o r B i o r e n e w a b l e C h e m i c a l s ( C B i R C ) a t I o w a S t a t e U n i ve r s i t y
W eb s i t e : www.gk12.iastate.edu E m a i l : symbi@iastate.edu
There is no direct connection to biorenewables
Additional Uses & Comments:
As noted in the “math connection” section above, this activity can be used to demonstrate linear
relationships and linear equations.
Deliverables:
*See following pages for deliverables to students and to implement this lesson plan into your
classroom. This was originally used as part of a “stations” activity, so the relevant parts of that activity
have been copied to this lesson plan.
Today's Activity
1) Form into table groups. Ms. Stewart will tell everyone the group size.
2) Go to each of the stations, read the instructions at the table, and carry out the activity.
3) Record your observations and answer the questions.
4) When time is called, you must go to the next table.
Types of Energy
Kinetic – Energy observed in the form of motion
Potential – Stored energy that can potentially be released
Thermal – The transfer of heat, leading to a change in temperature
Chemical – Energy that comes from making and breaking chemical bonds
Electric – The flow of electrons through a substance
Light/Radiation – Electromagnetic waves, some of which can be seen as light
Sound – Vibrations in solids, liquids, and gases that can be heard
Nuclear – Energy associated with the splitting of atoms
D e ve l o p e d b y: S ym b i , I o w a S t a t e ’ s G K - 1 2 P r o g r a m wi t h t h e N a t i o n a l S c i e n c e F o u n d a t i o n
E n g i n e e r i n g R e s e a r c h C e n t e r f o r B i o r e n e w a b l e C h e m i c a l s ( C B i R C ) a t I o w a S t a t e U n i ve r s i t y
W eb s i t e : www.gk12.iastate.edu E m a i l : symbi@iastate.edu
Station: Penny Batteries
1) What types of energy did you observe, and where did you observe it?
Type of energy
Found at
__________________ __________________ __________________
__________________ __________________ __________________
2) Since we can get pennies and washers to make electricity in this battery, why don't they normally zap
us when we touch them?
________________________________________________________________________________
________________________________________________________________________________
Table: Penny batteries
Materials
4 each of: Pennies, zinc washers, matboard discs. 1 LED, electric tape, and vinegar
Procedure
1. Soak 4 matboard discs in vinegar
2. Build a stack with the following: 1 penny, 1 piece of vinegar-soaked matboard, 1 washer
3. Put 4 of these stacks on top of each other, so that it looks like:
washer
matboard
penny
washer
matboard
penny
and so on.
4. Make sure no liquid is dripping out. Touch one of the LED contacts to the top, and one contact to the
bottom, so that it lights up.
5. Wrap the whole thing in electrical tape so it is nicely sealed.
6. Take this home and show your parents!
D e ve l o p e d b y: S ym b i , I o w a S t a t e ’ s G K - 1 2 P r o g r a m wi t h t h e N a t i o n a l S c i e n c e F o u n d a t i o n
E n g i n e e r i n g R e s e a r c h C e n t e r f o r B i o r e n e w a b l e C h e m i c a l s ( C B i R C ) a t I o w a S t a t e U n i ve r s i t y
W eb s i t e : www.gk12.iastate.edu E m a i l : symbi@iastate.edu