Pendulum Experiment- Part 2
Lesson 5 of 11
Objective: SWBAT use a pendulum based on Galileo's work to test different variables.
Unit 3: Gravity
Lesson 5: Re-Creating Galileo's Pendulum Experiments- Part 2
5E Lesson Planning:
I plan most of my science lessons using the BSCS 5E Lesson Model: Engage, Explore, Explain, Elaborate, and Evaluate.For a quick overview of the model, take a look at this video.
I use this lesson model because it peaks the students' interest in the beginning during the "Engage" portion and allows for the students to actively participate in the investigations throughout the subsequent steps. The “Evaluate” component of the 5E Lesson Model can be used in many ways by the teacher and by the students.
In this Unit students will do some investigations about gravity. They will learn about how the planets stay in orbit around the Sun and will re-create Galileo’s pendulum experiments. They will also learn about Sir Isaac Newton’s work and his Laws of Motion as they relate to the idea of gravity.
In this lesson, students will use a pendulum or swinger and change different variables to investigate different outcomes (whether or not the cycle changes). They will be conducting a controlled experiment, similar to the experiments Galileo performed. This is the second lesson in a 3 part investigation with pendulums.
The materials needed for this investigation per group are:
- 2 strings that are 50cm in length
- 2 regular paper clips
- 1 meter tape
- 2 pennies
- 2 pencils
- 2 direction sheets- How to build a pendulum/swinger. (Put link to attachment here)
Other supplies needed: scissors, watch or clock with a second hand, masking tape, and extra copy of the direction sheet to project or made into a poster for reference.
Next Generation Science Standards:
The NGSS standards that will be covered in this unit/ lesson are:
5-PS2-1. Support an argument that the gravitational force exerted by Earth on objects is directed down.
Disciplinary Core Ideas: This lesson aligns to the Disciplinary Core Ideas of PS2.B: Types of Interactions- The gravitational force of Earth acting on an object near Earth’s surface pulls that object toward the planet’s center. (5-PS2-1)
Cause and Effect: Cause and effect relationships are routinely identified and used to explain change. (5-PS2-1)
Science & Engineering Practices:
I ask the students to talk in their science groups about what we did during our last science session using a "Round Robin" cooperative learning strategy. We review what the definition of a variable is and we talk about the 3 variables from our previous investigation that might have affected the number of times the pendulum swung in 15 seconds.
I write these 3 variables on the board: Mass of the penny (bob), the release position, and the length of the string.
I explain to the students that we will be doing an experiment and define what this means. I have them copy the term and definition in their notebooks. I say that even though we've been doing a lot of science investigations and making models, this is our first true "experiment". I let them talk about what they think an experiment is and let them share some ideas.
We define experiment as an investigation designed to find out how variables affect outcomes. I tell the students that today we will be conducting a controlled experiment and we define this as an experiment where one variable is changed and the others are kept the same and the results are compared to the original or standard experiment.
I remind the students that the original or standard experiment was the one we set up the previous lesson and had the string at 38cm long, the bob was only 1 penny, and the release position was straight out to the side (parallel to the floor). This will now be referred to as the standard system.
In yesterday's lesson the students created a pendulum using the string, paperclip, penny, masking tape and pencil. I have the students gather the materials from the previous session and I ask them how many times their pendulum swung.
Testing Release Position:
I tell them that we are going to first test the variable of release position and that instead of holding the mass (penny) straight out, they will hold it at a 45 degree angle and will keep all of the other variables the same. Before we do this, I ask them to make a prediction of how the cycle might change and I record their answers on the board. The students then set up their pendulums and I give them protractors to measure 45 degrees from where the pendulum is hanging from the pencil. I tell them that all of the other variables remain the same since this is a controlled experiment. I have them record their results on the pendulum data sheet. Here is a student testing a different release point and another student testing a different release point.
Testing Different Masses:
The next variable we change is the mass or number of pennies that we use on the bob. I ask them if they think that changing the mass will change the number of swings- if they think it will cause more swings, less swings, or that it will stay the same. I give each partnership another penny to add to their set up and I tell them that the other 2 variables don't change- the length of the string and the release position are back to the standard experiment. (I have these variables listed on the board for students to refer to and draw in their Science Notebooks.)
We repeat the experiment with the new variable and the students count the number of swings in 15 seconds and record their data. If time allows, I let the students try this with 3 or more pennies so they can see what happens (they should still be getting the same number of swings each time). Here is a student doing the pendulum variable change mass where he is using 4 pennies to test the pendulum.
Testing Different Lengths:
I then explain to the students that we will be making new swingers with different length strings. Each partnership will get a different length of string and will make a new pendulum the same way we made them before (they can use their original pendulum for reference).
I give each partnership a different length of string ranging from 13cm to 200 cm. For the longer strings, we need to attach the pendulum to a higher anchor position (I remind the students of safety issues related to this.) I then give them this pendulum data sheet- lengths to record their data and later the other groups' data to compare results.