Cause and Effect: Force, Energy, and Simple Machines

Third Graders at HSA-DE continued their fourth Interdisciplinary Unit of Study during the third quarter with an exploration of physical science.  This Interdisciplinary Unit, titled "Cause and Effect" focused on physical science topics of Forces, Energy, and Simple Machines.  As previously written about here at Down the Hall in Room 177, in Social Studies, we focused on Citizenship and Government (Cause and Effect Social Studies).

To kick on the physical science aspect of our Cause and Effect Unit, we began by examining the front cover of the book How do You Lift a Lion? by Robert Wells.

Students were posed the question and were asked to come up with possible solutions to this dilemma. Each student was given a post-it note on which to write three ideas for how to lift the lion.  Next,  They worked in their P.R.I.D.E. groups to compare their ideas and generate a group lists of ideas for how they might lift a lion.  Finally, a whole class discussion was held and ideas were shared.

Some ideas for how to life a lion included:

1. Have a whole bunch of people lift different parts of the lion up all at once.
2. Use a helicopter and straps to lift it up.
3. Use a rope and pull it up.
4. Put it on a swing.
5. Push it up on a truck.
6. Use a tow truck to pull it up.

Following this, we began experimenting with force and motion.  Students learned that a force is something that changes the motion of an object.  We learned that there are many things that are forces.  For example, pushes and pulls are forces.

Students were shown a picture of Dr. Doolittle's famous creature the Pushmi-Pullyu.

They were asked how they thought this creature might move.  Students discussed this question with their table partner and eventually the class decided that while one half of the creature pulled, the other half pushed.  When asked what would happen if both halves of the creature tried to walk forward (away from each other) students realized that the Pushmi-Pullyu probably would not move much.

Following this discussion, students participated in a motion lab.  Students worked in P.R.I.D.E. groups as they moved through five centers.  At each center students were presented with a task where they would put small objects in motion.  They were to answer questions such as, "What was the force?" and "What made the object stop moving?"

Khadijah, Da'Marieon, Lavon, and Jayda PUSH a car across
the carpet to put it in MOTION.  Many things can cause the car
to stop moving or slow down.  One thing is if it CHANGES DIRECTION.
Another is the FRICTION of the tires against the carpet.

Dymond, Karissa, Shy'Diamond, and Marcus experiment with what happens
when two marbles are PUSHED towards each other.  They CHANGE
DIRECTION when they hit each other and eventually stop moving.

Darren, James, and Cayla observe difference between when a
bouncy ball is dropped from two different distances:  lower to the
ground and higher from the ground.  When the ball is dropped from higher
up, it bounces back higher.  GRAVITY is the PULL that makes the ball
MOVE to the ground.  The ground is the PUSH that makes the ball
bounce back up.  When there is more FORCE (dropping the ball from
higher up) there is faster MOTION.

Adriana works at one center where the students were to spin a top.  The FRICTION

created by the top rubbing against the surface of the desk stopped the top from moving

Mairon, Kaylin, and TaMya experiment with the force of wind
on a pinwheel.  

Ra'Jhay, Ray'Von, Adriana, and Aaron experiment with the force of wind on a liquid.

Next, students observed and experimented with friction and how the surface and object is being moved across effects the amount of work necessary to complete a task.  To demonstrate this, we used a spring scale.  A spring scare measures force needed to move an object in Newtons.  A stack of text books was bound together and pulled across a table, which is a smooth surface,  using the spring scale.  Measurements were taken and data was recorded.

Students record data after a stack of books was pulled across the table using a
spring scale.

Next, we repeated the test the same with with a rough surface.  Several bumpy ceramic tiles were places on top of the table and held in place by the students.  The stack of books was pulled across the tiles and the force needed to move the books was recorded.

Students working together to move a stack of books across a rough surface.

Finally, students experienced what happens when a lubricant is added to a surface.  LUBRICANTS are substances that can make work easier.  For our experiment, we used dish detergent on our table.  We pulled the stack of books across the table.  The books slid very easily across the table.

The students conclusion was that it took the least force and was easiest to move objects over a surface with a lubricant.  Next easiest was a smooth surface.  Finally, it took the most force, and was most difficult to move objects over a surface with a rough surface.

Students began to understand the key vocabulary involving force and motion:

ENERGY:  the ability to cause movement or change

FRICTION:  a force caused by objects rubbing together that makes them slow down or stop

FORCE:  a push or a pull

MOTION:  movement of something from one place to another

PUSH: a force that moves an object away from another object

PULL:  a force that moves an object towards another object

GRAVITY:  a force that pulls objects towards each other
POSITION:  where an object is located

So, next we discussed things that help us do WORK.  WORK is what is done when something is done to move an object over a distance.  We revisited How do You Lift a Lion? by Robert Wells.  By reading this book, students were exposed to their first discovery of simple machines.  In the book various animals were moved by using levers, pulleys, inclined planes, screws, wheels & axles, and wedges.  Each day, for a week, students learned about one simple machine.

Da'Marieon and Khadijah experiment with load, fulcrum and lever.

On the last day of this unit, students looked through advertisements from Lowes and Menards to find simple machines.  They made collages of items found in these ads that were examples of simple machines.