# Engage: Force

Locate a timer or stopwatch, and sit down in a chair. Make sure your feet touch the floor.

Feel the soles of your shoes. Do they feel cold, cool, room temperature, warm, or hot?

Did you say cool or room temperature? If so, you are correct!

Place both feet flat on the floor. Move them quickly back and forth for 5-10 seconds making sure they continuously touch the floor. Immediately feel the soles of your shoes.

Do they feel cold, cool, room temperature, warm, or hot? Is that different from how the soles of your shoes felt before moving them back and forth on the floor?

What kind of energy was generated by moving your shoes? That's right! Heat/thermal energy!

Now, place your feet flat on the floor again. Move them quickly back and forth for 15-20 seconds. Don't stop until time is up! Immediately feel the soles of your shoes.

Do they feel cold, cool, room temperature, warm, or hot? Depending on what your shoe soles are made of, you may have different answers to this question than your friends.

Did you feel a greater difference in the temperature of your shoe soles after rubbing them on the floor for a shorter amount of time or longer amount of time? Most people will say that rubbing their shoe soles on the floor for a longer amount of time will make them feel warmer.

Were there any forces involved in moving your shoes back and forth on the floor? If so, which one(s)?

# Explore: Experimenting with Force

Have you ever had a question about how something works? Why it works? What might happen if you changed this or that? If so, what comes next? How do you answer the question?

Scientists follow a process of investigation when trying to find answers to their questions.

• Question: A question is asked based on what a scientist wants to know.
• Hypothesis: A hypothesis is a prediction stating what a scientist thinks will happen in an experiment.
• Materials: The materials list details what supplies a scientist will need to conduct an experiment.
• Procedure: A procedure is a set of instructions detailing how scientists are to conduct an experiment.
• Data Collection: As scientists do an experiment, they can record their observations and data in a table.
• Results: Scientists analyze their results and devise a conclusion based on their findings.
• Conclusion: Scientists reflect back on their predictions, or hypotheses, to see if they predicted the correct outcome. They also list the things that were done well in the experiment as well as the things that could have been done differently or better.

​You have the opportunity to do three different experiments to see how this process works! Click on View Related Items to download and print the instructions and recording pages for each experiment. Ask your teacher to help you collect the materials to do the experiments.

Experiment A:

Is more force needed to move an object resting on carpet than an object resting on tile?

Experiment B:

Are some magnets stronger than other?

Experiment C:

Is more force needed to move heavier objects?

# Explain: Forces Among Us

Read and discuss Forces among Us with a partner or small group. Click on View Related Items below to download and the book.

Let's investigate magnetism! Follow the directions on the screen and make observations.

Which magnet was the strongest? How do you know?

Now, let's investigate gravity! Select two items, and observe what happens when they  are dropped.

No matter which two items are dropped, they fall to Earth's surface. This is the result of gravity!

Lastly, let's investigate friction! Follow the directions on the screen and make observations.

Observe how far the car rolls on different surfaces. The farther the car rolls, the less friction exists between the car and the road!

# Elaborate: Designing an Experiment

Are you ready? Do you have any questions about force you can answer with an experiment? It's time for you to do just that! Design your own experiment to test the effects of force.

Click on View Related Items to download and print Elaborate Designing an Experiment. Plan and write out your experiment first. Ask your teacher if the needed materials are available and if the procedure makes sense. Once your teacher approves your investigation process, you're good to go! Conduct the experiment, record your results, analyze the data, and formulate a conclusion.

Describe a time in your life when you experienced friction. Was it a good experience or a bad experience? Would it have been better if you had experienced more or less friction?

# Evaluate: Designing an Experiment Assessment

Work with a small group to complete Designing an Experiment Assessment. Click on View Related Items to download and print the assignment.

# Teacher Notes

Engage

The force of friction is first introduced in fourth grade. Students may or may not know about the force of friction at this point in the lesson. This activity addresses friction defining it. We will define friction in the Explain portion of the lesson.

Explore

Help your students collect the materials to do these experiments. Push-pull spring scales can be purchased from science material suppliers. Spring scales need to measure force in newtons. Bath towels can be cut into sections and taped down to substitute for carpeted areas in Experiment A.

Facilitation Questions

Experiment A

• What were you testing? I was testing whether it took more force to pull a book on carpet or tile.
• What was the only difference in your experiment? The only difference in my experiment was the kind of flooring I used: carpet or tile.
• Why did you pull the book three times on each surface? I pulled the book three times to make sure the results were as consistent and reliable as possible.
• What things stayed the same in your experiment? The things that stayed the same in the experiment were that I used the same book on both surfaces, I pulled the book with the same amount of force each time, I pulled the book the same distance on both surfaces, and I used the same spring scale and meter stick to take all measurements.
• Why is it important to have only one difference in an experiment? I need to know what is causing the results in the experiment. For example, if I used different sizes of books and different types of flooring, I would not know whether the size of book or the type of flooring was affecting the results of the experiment.
• Was more force needed to pull the book on carpet or tile? More force was needed to pull the book on carpet.
• Why was more force needed to pull the book on one surface than the other? Answers will vary but may include that more force was needed to pull the book on carpet because carpet is rougher or bumpier than tile.
• Were all your measurements the same? If not, why not? Answers will vary but may include that the data was relatively the same with an exception. This could be a result of pulling with more or less force during a trial.
• Why did you repeat the experiment? I repeated the experiment to make sure I was getting accurate measurements and reliable data. If a scientist does an experiment only one time, he or she might not collect reliable data. The experiment needs to be repeated to make sure the data is similar each time.

​Experiment B

• What were you testing? I was testing which type of magnet was the strongest.
• What was the only difference in the experiment? The only difference in the experiment was the kinds of magnets used.
• What things stayed the same in the experiment? The things that stayed the same in the experiment were that I used the same metric ruler and paper clip and moved the paper clip 1 cm each time.
• Why is it important to have only one difference in an experiment? I need to know what is causing the results in the experiment. For example, if I used different kinds of magnets and different types of magnetic objects, I would not know whether the different kinds of magnets or the different types of magnetic objects were affecting the results of experiment.
• Which magnet proved to be strongest? Answers will vary based on the magnets used.
• Were all the measurements the same? If not, why not? Answers will vary but may include that some answers were similar while others were not. This could be a result of releasing the magnet instead of holding it in place the whole time or pushing the paper clip instead of moving it forward and releasing it. Magnets lose strength if they are dropped, which could also affect the results.
• Why did you repeat the experiment? I repeated the experiment to make sure I was getting accurate measurements and reliable data. If a scientist does an experiment only one time, he or she might not collect reliable data. The experiment needs to be repeated to make sure the data is similar each time.

​Experiment C

• What were you testing? I was testing whether it took more force to move an empty container or a container filled with gravel, rocks, or dry beans.
• Was you hypothesis correct? Answer may vary.
• What the only difference in your experiment? The only difference in the experiment was the mass of the containers.
• What things stayed the same in the experiment? The things that stayed the same in the experiment were that I used the same surface, I pulled the containers with the same amount of force each time, I pulled the containers the same distance on both surfaces, and I used the same spring scale and meter stick to take all measurements.
• Why is it important to only have one difference in an experiment? I need to know what is causing the results in the experiment. For example, if I used two different containers and two different surfaces, I would not know whether the different containers or the different surfaces were affecting the results of the experiment.
• Was more force needed move Container A or Container B? More force was needed to move Container B.
• Why was more force needed to move Container B? Answers will vary but may include that Container B is heavier.
• Were all of your measurements the same? If not, why not? Answers will vary but may include that some answers were similar while others were different. This could be a result of pulling with more or less force from one trial to another.
• Why did you repeat the experiment? I repeated the experiment to make sure I was getting accurate measurements and reliable data. If a scientist does an experiment only one time, he or she might not collect reliable data. The experiment needs to be repeated to make sure the data is similar each time.

Explain

The literacy book, Forces Among Us, is content heavy. Stop frequently to ask students if they have questions or need clarification.

Force is defined as a push or a pull. Magnetism, gravity, and friction are all forces. Spring scales are tools that measure force using the metric unit of newtons.

Students will design experiments to test the effects of force on an object. Each group must develop a question it can answer with an experiment. Groups will develop a hypothesis or a prediction about what will happen in their experiment. A hypothesis also serves as a predicted answer to the question the group asks. Groups will need to construct materials lists based on what they need to do their experiments. Next, groups need to write a procedure detailing how to do their experiments. During the experiments, students will collect data, analyze the results, and come to conclusions. Remind students to repeat their trials (or experiments) at least three times to make sure the data is reliable.

After reading and discussing Forces among Us, students will work through the online activities for the forces of magnetism, gravity, and friction.

Elaborate

Students will be designing their own experiments to test the effects of force in this portion of the lesson. Some students may need you to provide them with questions. Have various materials on hand for students to use.

Allow students to work in small groups to design their experiments. Examples of experiments may include the following:

Does friction affect magnetism?

Students may choose to test this question by following a similar set of instructions as was used in Experiment B of Explore. Students may use two horseshoe magnets positioned 10 cm away from each other on tile. While holding one magnet in place at 0 cm, the other magnet would be moved 1 cm at a time from 10 cm toward the magnet at 0 cm. This experiment would then be repeated on carpet to see if friction affected the distance between the two magnets when attraction was first observed.

Is magnetism more powerful than gravity?

Students may choose to test this question by following instructions similar to the previous experiment. The only difference would be that the metric ruler would be vertical. The magnet resting at 0 cm would not be held in place. Instead, the magnet being moved closer to the magnet at 0 cm would be held in place after each 1 cm move forward. Students would determine whether magnetism is more powerful than gravity based on whether the magnet being moved toward 0 cm could eventually pick up the magnet resting on the floor.

Does friction affect how far an object will roll?

Students could create ramps of equal height and size and cover each with a different material, such as carpet, sand paper, or waxed paper. A ball or toy car could be rolled down the ramps with various coverings. Students would measure how far the object rolled after it reached the bottom of the ramps. Alternately, students could use only one ramp but set it up on different surfaces such as carpet, tile, or concrete. Again, students would measure how far the object rolled after exiting the ramp.

Science Notebook Entry

Answers to the notebook entry may include:

• Slipping on a wet floor and bruising your leg or breaking your arm
• Putting snow chains on tires to avoid slipping on ice
• Sliding into base during a ball game to avoid being tagged out
• Hydroplaning on a wet road due to a lack of tread on tires on having a wreck
• Sledding down a snow-covered hill to experience speed
• Sliding down a playground slide or water slide and not getting stuck

Evaluate

Students may work in groups to complete the assessment.

1. What did the students do correctly?

The layout of the experiment was done well. A question, hypothesis, materials list, procedure, data, and results were all part of the plan. The students repeated the experiment to record more data. The students used the same size books, ramp, toy car, and meter sticks. the students measured and recorded their data in a table.

2. What could the students have done better?

The students should have used the same number of books to place under each ramp. They were testing to see if the car would travel farther on carpet than tile. The height of the books should not be a factor in the experiment.

The same student could have released the car to make sure it was done the same way each time. Judging by Trial 3 on tile, it looks as if someone may have pushed the car instead of releasing it since the distance traveled was much greater than in Trials 1 and 2.

3. Based on the experiment, is the students' hypothesis supported by their data and did they design the experiment to find a true answer to their question? Why or why not?

The students' hypothesis is not supported by their data according to the results. The students did not design the experiment to find a true answer to their question because they had two differences: the type of flooring and the height of the ramp. In order to find a true answer, the students would need to redo the experiment using the same ramp height on both types of flooring.