Day 2: Science
1. Topic: Discovering how a car works
2. Estimated time: 80 minutes
a. Students will be able to understand the four basic steps in the four stroke
internal combustion engine.
b. Students will develop estimation/hypothesizing and observation skills.
4. Materials needed:
a. Power point projector and computer to show clips to the class
b. Internet access
c. Potato gun or tennis ball gun (easy to make if you don’t have one. Directions are
easily found on line http://dangerouslyfun.com/spud-gun).
d. Different projectiles,
i. a paper cup
iii. Tennis balls
e. A couple of cans of hairspray.
f. Large Open field
g. diagram sheet for internal combustion
h. Video camera
a. Start by asking the class what I am holding?
b. Have a potato gun, and call it a model of an internal combustion engine.
c. Give a talk about the process that happens in the chamber using a diagram or a
dissected potato gun. Power point for quick explanation.
d. Take the class to a large open outside field.
e. Have everyone stand safely behind a backstop and shoot the gun using a Nerf
ball, sock, or a potato.
f. BE VERY CAREFUL WHICH WAY YOU SHOOT IT. These guns have unpredictable
ranges. The potato/projectile could be going very fast and could potentially
harm someone or damage something.
i. Give demonstration of the potato gun
ii. While still outside ask the students, what the components of the system
are. Prompt with questions if students do not come up with a few on
their own. Explain the five main components.
1. A Flammable Fuel
5. What is the Output= kinetic energy, linear motion (the line of the
path of the potato).
iii. Ask students what forms of energy are present in the system. Students
may not know so give a simple description of three energy forms.
1. Chemical potential energy (stored energy in the chemicals)-
hairspray is transferred to…
2. Kinetic energy(movement)- potato
3. Thermal energy-from combustion
g. Have the class pick up the potatoes, Nerf Balls, or other projectiles. Have fun
with how far it shot different projectiles, have students hypothesize which
projectile will shoot the furthest. Count steps shot from gun, estimate how far
that is in meters; estimate height, etc. This will develop the students’ estimation
skills. It is fun to see how far the different projectiles will shoot out, the shortest
distance (there are usually some poor shots, projectiles will not consistently fly
h. Have class move back inside.
6. Lesson Steps:
a. Using a power point projector or Smart Board show a How Stuff Works video clip
5 minutes long- this could be done instead of using the real potato gun. It has
some great illustrations and applications.
b. Lecture on the internal combustion engine and the basic four stroke engine.
http://www.familycar.com/Engine.htm these are excellent sites to explain the
process of internal combustion and how that relates to moving a car.
c. Write the four steps (intake, compression, power, exhaust) on the board as
described below or print as a fill in the blank outline.
i. Four steps **All through these steps the teacher would be drawing on
the board, overhead or smart board. Students will get a copy of the basic
engine block that they would have to label and fill in with arrows as we
went through the steps. Sample diagrams.
a. Turn the key, INTAKE VALVE is open and lets in a mixture
of air and gasoline. This mixture fills the chamber.
b. The Piston moves from top to bottom of the chamber,
when it is at the bottom the INTAKE VALVE closes.
i. intake valve=open
ii. exhaust valve=closed
iii. piston position=bottom
a. The piston pivots at its base and moves upward
compressing the gasoline and air mixture.
i. the base of the piston is moving in a circular
motion, all pistons are connected to the crankshaft,
ii. crankshaft is moving, what kind of energy? Kinetic
b. The air is trapped, and very compacted.
c. What do you think happens when you compress air/gases?
The pressure increases.
d. Use a balloon, compress; more pressure is more potential
energy. (At a particle level the atoms are bouncing around
faster, thus they will leave faster).
e. Intake valve=closed
f. Exhaust valve= closed
g. Piston position= top
3. Power/Combustion stroke
a. Spark is sent from the spark plug. The spark ignites the
fuel and causes an explosion and expansion of air. Forcing
the Piston down again turning the CRANK SHAFT to propel
b. Use the balloon, squeeze, pin=spark, pop=combustion,
flying balloon parts=exhaust
c. What part of the potato gun. Rather than having a potato
in the end of the gun we would have a ___________? A
piston connected to a crankshaft.
d. Connected to the piston is the crankshaft.
e. The explosion forces the piston down the chamber.
f. The potato is like the piston, it moves in response to the
g. In a combustion engine the piston turns the crank shaft
resetting the process, the piston doesn’t fly out every time
there is combustion.
h. Intake valve=closed
i. Exhaust valve= closed
j. Piston position= bottom
a. After the combustion the piston is driven down and the
EXHAUST VALVE opens.
b. The gas is under such pressure that it leaves the chamber
with a lot of force, and a lot of noise.
c. The piston moves up the chamber to begin the process
again. Notice how the piston is always moving.
d. Have you ever noticed when a car doesn’t have a muffler
on it? It sounds very loud and sort of like a gun shot.
a. Have the students get into groups of four and act out the internal combustion
engine, each group will present to the class their reenactment of an internal
combustion engine. This could be videotaped to be recorded in their portfolio.
Students will get a simple completion mark if they acted out all four parts of the
combustion process using all their group members.
b. Quickly review the four phases of internal combustion, identify on the potato
gun the exhaust, the piston, the intake valve. (Exhaust in a combustion engine is
= the shooting end of the potato gun. Intake in a combustion engine is like the
back end of the potato gun, where you load hairspray. The piston in the
combustion engine is like the potato in the potato gun.)
a. Basic in class-
i. Students will label and complete the diagrams of the internal combustion
ii. Have students act out the internal 4 stroke combustion engine in class.
Each group must write a little about their skit to remember it. These skits
can be videotaped.
i. Find an interesting fact about cars or a news article related to cars.
Students can use the Book of World Records.
ii. Ten point quiz in class another day. See quiz.
a. Check student’s diagrams for completion, if completed they get one point
b. Evaluation of the students’ group skits. See rubric.
c. Check for students interesting fact about cars or a news article. Place on the
bulletin board. Students will have to share a bit about their article or share their
fact with the class when they bring it in. They will get a completion grade
a. Give a ten point ten question quiz on the terms learned in the lesson.