Forces: A Learning Cycle
Science Concept: A force is a push or a pull. Unbalanced forces cause motion, balanced forces do not.
Age/Grade of Students: 6-8th graders, mostly
10 to 14 years old.
TEACHER’S GUIDE
Forces: A Learning Cycle
Concept:
A force is a push or a pull. Unbalanced forces cause motion, balanced forces do not.
Materials:
Open area with 5-10 m diameter circle, rope, block of wood with hooks in opposite ends, two spring scales, gloves, helmets, paper, and pencil
Safety:
A soft or grassy surface is preferred, and helmets and gloves are recommended for both the “reverse sumo” and tug of war.
Procedures:
See Teacher’s and Student’s Guides
Assessment:
-Completion and class discussion of questions on student’s guide.
-Appropriate practice problems.
-Quiz or test.
-Completion of Expansion(s) with discussion and observation to facilitate and confirm student understanding.
TEACHER’S GUIDE
“A TUG OF WAR”
EXPLORATION PART A:
TEACHER NOTE: Explain each setup and have students make predictions before each game.
On the first setup evenly split the class into two separate teams.
On the second setup move 5 players from the red team and put them on the blue team to create a team with a larger number. (Numbers may vary depending on class size.)
On the third setup pick students who are the strongest and put them on the team with the lowest number of players. (Keep the ration the same as in the second setup.) For each setup, play 3 games and have students record their information between each trial.
Prediction 1:
Who do you think will win the most of three games? RED BLUE (circle one)
Why? Answers will vary. Students may say something about strength or size
because the numbers are the same.
Prediction 2:
Who do you think will win the most of three games? RED BLUE (circle one)
Why? Students will probably say the blue team will win because they have more
people.
Prediction 3:
Who do you think will win the most of three games? RED BLUE (circle one)
Why? Students will either predict the team with the strongest members OR the
team with the most members. Either will be accepted.
TEACHER’S GUIDE
Number on each team
Game 1
Game 2
Game 3
Team with most wins
Red _____
Blue_____
Red _____
Blue_____
Red _____
Blue_____
You may want to make a copy of the table for the overhead or put the table on the board.
When the teams were even who won the most games? Why? Answers will vary,
Explanation may be because a student is stronger or bigger.
When the teams were uneven who won the most games? Why? Students may
say the team that had the most people.
When the teams were divided by size, who won the most games? Why? Students
may say the team with the most members or the team with the stronger players.
Were your predictions correct or incorrect? Explain. Answers will vary.
TEACHER’S GUIDE
PUSHING EACH OTHERS “BUTT”ONS
EXPLORATION PART B:
TEACHER NOTE: The gym was suggested because it already has circles on the floor. You may also want to tape down a 2m X 2m square to use if you want more than one group to go at a time. Teacher will line up 2 students back-to-back at the center line. When the teacher blows the whistle the students will attempt to push each other out of bounds. The students may not use their hands to accomplish this and must stay back-to-back. If they fall or become disconnected they reconnect and begin again. The game ends when one student is pushed out of the circle or square. Have students record the winner in their table.
1. Who won the most games in your group? Explain why this happened.
Answers will vary depending on results.
2. Did the size of the person determine who won? Why or why not?
Answers will vary depending on results.
TEACHER’S GUIDE
IDEA
Go over the answers to the IDEA page.
Students may not come up with the idea that a force is a push or pull. Teacher may have to invent the term force. It needs to be stated that the change in motion that is experienced in these activities indicates that a force is present. For example, when the rope is not in motion and is stopped, a force is applied. Teacher should also express to students that even if the object is not moving a force may still be applied.
1. During the tug of war game, was the rope in motion before the rope was
touched? The rope was not in motion before it was touched.
2. How do you know if the rope was or was not in motion? We know the rope
was not in motion because the bandana was not moving toward or away from
the reference point.
3. What observations about the rope did you make when the game of tug of war
began? What caused this to happen? Answers may include the rope is
moving or starts moving. Students may say this is caused because they are
pulling on it. Some students may also bring the term force out at this time.
4. At any point in the game was the rope not in motion? If so, when and why?
The rope was not in motion when both teams were pulling with the same
strength on both ends.
5. In exploration A, what action was taking place? pulling
6. In exploration B, what action was taking place? pushing
7. Do the actions in the explorations have the ability to cause an object to move?
Yes, both pulling and pushing can cause an object to move or change
direction.
TEACHER’S GUIDE
IDEA CONT.,
8. Are the actions described above, considered to be forces? Explain. At this
point, hopefully students can say yes because pushing or pulling is applying
a force.
9. What idea do you have about forces? Students should say that a force is a
push or pull and can cause a change in motion.
10. Do forces always cause the object to move? Explain. Forces do not cause
objects to move. For example, in the tug of war game when the equal force is
being applied to both sides of the rope.
11. Give your definition of what a force is. Answers will vary but students should
state that a force is a push or a pull. Unbalanced forces cause motion,
balanced forces do not.
TEACHER’S GUIDE
“A BALANCING ACT”
EXPANSION
Teacher may want to make an overhead or put on the board the tables so that the results may be discussed as a group. Teacher also needs to explain the proper use of a spring scale.
Procedure:
1. Using the tape the teacher provides, tape a center line on the desk.
2. Place the object evenly on the center line.
3. Attach a spring scale to each side of the object.
4. Each person pulls with a force of 1 Newton.
5. Determine whether or not the object is in motion using the tape line as a reference point.
Student #1 Force
Student #2 Force
Did the object move?
Were forces equal?
Are the forces working in the same or opposite direction?
1N
1 N
Repeat activity with one student pulling with a force of 1 Newton while the other
Student does not apply a force.
Student #1 Force
Student #2 Force
Did the object move?
Were the forces equal?
Are the forces working in the same or opposite direction?
1N
0 N
Repeat activity with both students pulling with a force of 1 Newton on the same
side of the object.
Student #1 Force
Student #2 Force
Did the object move?
Were the forces equal?
Are the forces working in the same or opposite direction?
TEACHER’S GUIDE
Balance forces are when the forces are equal or unequal.
Balance forces cause motion or do not cause motion.
Unbalanced forces are when the forces are equal or unequal.
Unbalanced forces cause motion or do not cause motion.
Give a definition of balanced forces based on your information or observation.
Balanced forces are when equal forces are applied in opposite directions.
Give a definition of unbalanced forces based on your information or observation.
Unbalanced forces are unequal forces applied in opposite directions. Students
may also say when 2 forces applied in the same direction.
Give an example of a real life situation in which there are unbalanced forces.
Students may say kicking a soccer ball, closing a door, opening a drawer. Other
possible answers will be accepted.
Give an example of a real life situation in which there are balanced forces.
Answers may include leaning against a wall, telephone lines being held up or
other possible answers.
When the forces were applied in the same direction was it a balanced or
unbalanced force on the object? Explain. When forces are applied in the same
direction it will be an unbalanced force because there is nothing to prevent the
start of motion.
STUDENT’S GUIDE
“A TUG OF WAR”
EXPLORATION PART A:
Materials:
Tug of war rope
Gym or large area
Bandana
Procedure:
1. The rope is positioned so that the bandana is placed on the half court line.
2. Your teacher will divide the class into 2 EVEN teams.
3. Your teacher will assign your team a color and a specific end of the rope.
4. Your teacher will tell you when to start pulling.
5. When half of the team passes the center court line, the game is over and the teacher will instruct you to drop the rope.
6. Make a prediction before the game begins.
Prediction 1:
Who do you think will win the most of three games? RED BLUE (circle one)
Why? ____________________________________________________________
__________________________________________________________________
Now the teacher will divide the class into 2 different teams.
Prediction 2:
Who do you think will win the most of three games? RED BLUE (circle one)
Why? ____________________________________________________________
__________________________________________________________________
Now the teacher will divide the class into different teams again.
Prediction 3:
Who do you think will win the most of three games? RED BLUE (circle one)
Why? ____________________________________________________________
__________________________________________________________________
STUDENT’S GUIDE
TUG OF WAR CONT.,
Complete the data table with the results of each game by filling in the team that won.
Number on each team
Game 1
Game 2
Game 3
Team with most wins
Red _____
Blue _____
Red _____
Blue _____
Red _____
Blue _____
1. When the teams were even who won the most games? Why? ___________________
_______________________________________________________________________
2. When the teams were uneven who won the most games? Why? _________________
________________________________________________________________________
3. When the teams were divided by size, who won the most games? Why? __________
________________________________________________________________________
4. Were your predictions correct or incorrect? Explain. __________________________
________________________________________________________________________
STUDENT’S GUIDE
PUSHING EACH OTHERS “BUTT”ONS
EXPLORATION PART B:
Procedure:
1. Find a partner (only 2 per group).
2. Your teacher will instruct you where to line up back to back.
3. When the teacher blows the whistle, begin pushing your partner. You must stay back to back and you may NOT use your hands.
4. Repeat the procedure 2 more times.
5. Record the name of the winner in the table below.
Student #1 __________________________ Student #2 ___________________________
Trial 1
Trial 2
Trial 3
Most Wins
Find 2 other groups and record their information below.
Student 1__________________ vs. Student 2 __________________ Winner __________
Student 1__________________ vs. Student 2 __________________ Winner __________
Who won the most games in your group? Explain why this happened.
__________________________________________________________________
__________________________________________________________________
Did the size of the person determine who won? Why or why not?
_________________________________________________________________
_________________________________________________________________
STUDENT’S GUIDE
IDEA
During the tug of war game, was the rope in motion before the rope was touched?
_________________________________________________________________
_________________________________________________________________
How do you know if the rope was or was not in motion? ____________________
__________________________________________________________________
What observations about the rope did you make when the game of tug of war
began? What caused this to happen? ___________________________________
__________________________________________________________________
At any point in the game was the rope not in motion? If so, when and why?
__________________________________________________________________
__________________________________________________________________
In the exploration A, what action was taking place? ________________________
__________________________________________________________________
In the exploration B, what action was taking place? ________________________
__________________________________________________________________
Do the actions in the explorations have the ability to cause an object to move?
__________________________________________________________________
__________________________________________________________________
Are the actions described above, considered to be forces? Explain. ___________
__________________________________________________________________
STUDENT’S GUIDE
IDEA CONT.,
What idea do you have about forces? ___________________________________
_________________________________________________________________
Do forces always cause the object to move? Explain. ______________________
__________________________________________________________________
Give you definition of what a force is. __________________________________
__________________________________________________________________
STUDENT’S GUIDE
EXPANSION
Procedure:
1. Using the tape the teacher provides, tape a center line on the desk.
2. Place the object evenly on the center line.
3. Attach a spring scale to each side of the object.
4. Each person pulls with a force of 1 Newton.
5. Determine whether or not the object is in motion using the tape line as a reference point.
Student #1 Force
Student #2 Force
Did the object move?
Were forces equal?
Are the forces working in the same or opposite direction?
1N
1 N
Repeat activity with one student pulling with a force of 1 Newton while the other
Student does not apply a force.
Student #1 Force
Student #2 Force
Did the object move?
Were the forces equal?
Are the forces working in the same or opposite direction?
1N
0 N
Repeat activity with both students pulling with a force of 1 Newton on the same
side of the object.
Student #1 Force
Student #2 Force
Did the object move?
Were the forces equal?
Are the forces working in the same or opposite direction?
STUDENT’S GUIDE
Underline the bold word that completes the sentence correctly.
Balance forces are when the forces are equal or unequal.
Balance forces cause motion or do not cause motion.
Unbalanced forces are when the forces are equal or unequal.
Unbalanced forces cause motion or do not cause motion.
Give a definition of balanced forces based on your information or observation.
__________________________________________________________________
__________________________________________________________________
Give a definition of unbalanced forces based on your information or observation.
__________________________________________________________________
__________________________________________________________________
Give an example of a real life situation in which there are unbalanced forces.
__________________________________________________________________
__________________________________________________________________
Give an example of a real life situation in which there are balanced forces.
__________________________________________________________________
__________________________________________________________________
When the forces were applied in the same direction was it a balanced or
unbalanced force on the object? Explain. _______________________________
__________________________________________________________________
__________________________________________________________________
Bibliographic Note:
Edmund Marek and Timothy Laubach, "Bridging the Gap between Theory and Practice: A Success Story from Science Education", (M. Gordon, T. O'Brien (eds.), Bridging Theory and Practice in Teacher Education, 47-59. copyright 2007 Sense Publishers.
Edmund Marek and Ann Cavallo, The Learning Cycle: Elementary School Science and Beyond, (Portsmouth NH, Heinemann, 1997).
PASS Objectives, Oklahoma State Board of Education, 2002.
National Science Education Standards from the National Academy of Sciences, 1995.
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