Lesson Plan Template: General Lesson Plan
Learning Objectives: What should students know and be able to do as a result of this lesson?
- Students will be able to understand that the weight of any object is the force with which the Earth pulls down that object.
- According to Newton's Second Law, f = m x a, or for our specific example, w = m x g or g = w/m.
- Students will be able to understand that weight and mass are proportional, while the acceleration (gravity) will remain the same.
Prior Knowledge: What prior knowledge should students have for this lesson?
Students should be familiar with the following concepts:
- Gravitational acceleration
- Newton's First and Second Laws
Students should be familiar with the use of the photo gates and data collector. Please see the Recommendations section for details.
Guiding Questions: What are the guiding questions for this lesson?
If we make the friction with the air as small as possible, how does the mass of the object affect how fast it will fall?
Teaching Phase: How will the teacher present the concept or skill to students?
- As a demonstration, the teacher will drop a 50g cylinder and a coffee cup filter at the same time from the same height in front of the class. Make sure to have something to protect the floor!
- The teacher will ask students: Why don't they fall at the same rate? What happened?
- After the students come up with reasons, the teacher will make a paper ball from the coffee cup filter and will drop them again in the same way. This time, they should both land at about the same time.
- The teacher now asks students to explain why the two objects fall almost at the same time in the last trial.
Guided Practice: What activities or exercises will the students complete with teacher guidance?
The teacher will present the following question to the students:
If we drop a 10g cylinder, a 50g cylinder, and a 100g cylinder at the same time from the same height, which one will reach the floor first?
Students will express their opinions and make a hypothesis.
In order to support their hypotheses, students will investigate the following question:
How does the mass of the cylinder affect its velocity/acceleration when it is falling with reasonable small friction?
The teacher will provide students the equipment they need.
Students should attach the photogate heads to the stands so that that the falling cylinder will pass through the openings intercepting the light beams. Students should measure the distance between the photogate heads. To calculate the average velocity, students have to divide the distance between the photogate heads by the time given on the data collector.
The students will design the necessary tables to record the data. For each trial, they will need to make two graphs: one for displacement vs. time, and one for average velocity vs. time. Expect at least three trials.
The teacher should clarify that average velocity does not reflect the fact that the velocity actually is increasing over time.
Independent Practice: What activities or exercises will students complete to reinforce the concepts and skills developed in the lesson?
As homework for the next class, the students will make a free body diagram for a crate falling on Earth and on the Moon with a parachute at three different altitudes:
- at the 2000m just after it was dropped and the parachute released,
- at the altitude 1000m, and
- just before it hits the ground.
Assume the crate falls straight down.
Hints: There is not a significant atmosphere on the moon, and Earth is much more massive than the moon.
Closure: How will the teacher assist students in organizing the knowledge gained in the lesson?
The teacher will ask students to calculate the weights of the cylinders using Newton's Second Law: w= m x g
The teacher will ask two students to solve their calculations on the board.
The measurements and calculations should be very close. The teacher should ask students to explain why the measurements and calculations are not exactly the same.
The teacher will solve the formula for gravitational acceleration: g = w / m
The teacher will use these equations to make students understand that if no other force than weight acts on the falling object (in other words, if there is no friction), then any object will fall with the same acceleration, since the weight (applied force) and the mass change proportionally.
Students will present their homework orally the next day during class.
As a conclusion of the activity, each group will present their findings on two 2'x2' white boards. On each white board, students will reproduce a table including mass of the cylinder and average velocity. On the same white board, students will represent an average velocity vs. time graph. Students will be graded using the attached rubric. Grading Rubric
After the student's presentations, show the video of the Apollo astronauts repeating the famous Galileo experiment while on the moon: http://www.youtube.com/watch?v=WOvwwO-l4ps
This is the same experiment we are doing in class, but the astronauts don't have to worry about the friction of the air.
The teacher will present specific questions about free fall to students. Students will have the opportunity to express their opinions and make a hypothesis. The teacher will divide students into groups of five or six. Students in the same group don't have to have the same hypothesis.
Students will design an experiment to test their hypotheses. Each student will present a Lab Report in which the data is the same for the all members of the same group, but the format is not necessarily the same. On the report, the students will answer and explain the initial question.
Feedback to Students
The teacher will give feedback to each group after their presentations. If the results are different from what the group expected, then the teacher will ask students to explain the possible reasons. The teacher will ask each group to answer the initial question. The teacher will not deny or confirm any of the answers until the last group presentation.