Students have data from their roller coaster investigations and I now want to provide an opportunity for them to deepen their understanding of how energy transfers by investigating bouncing balls.
Students will see that the height of a bounce depends on the original height of the ball. They should also observe that the ball never bounces as high as the original height. The concept that I want students to ponder, which will lead to deeper understanding of energy transformations, is where does the energy go.
Students will begin by predicting what will happen when a super bouncy ball is dropped from above my head. Most students think that because it is a super bouncy ball that it will bounce exceptionally high. In fact, the ball only bounces about a third of the initial height -- similar to all other balls as they will discover.
After students observe this phenomenon they will have many questions, including why this happens? Where does the energy go? Does this happen with all types of balls? Does height affect how high the ball bounces?
After raising questions, they will plan and carry out investigations to find answers to their questions.
Upon collecting evidence from their investigations, students will find patterns in their evidence. There is an opportunity, if you so choose, to have students investigate properties of matter and how that relates to the height of bounces, but we will not be pursuing that here. We focus on finding patterns in our data and then comparing that to the outcomes from the roller coaster lab in this lesson.
The purpose of this lesson, overall, is to provide students with another phenomenon that deals with the same concepts of energy conservation and transfer of energy.
Hooking students' attention gets them excited to learn. In a boisterous voice, I welcome students to class and then ask them to make predictions about what will happen when I climb to the top of the chair, hold a SUPER bouncy ball above my head and release it.
I ask them to use P.E.O.E to predict what they think will happen and explain why they feel that way. This video walks you through the strategy. P.E.O.E. is a great strategy to implement at various points within most NGSS lessons. I discovered it towards the end of this school year and appreciated the ease of implementation, which was measured by the reception of my students. In that, they found the concept to be easy to understand. They also appreciate having their ideas and observations all in one place. From an educator perspective, you can quickly gauge your students' progress by glancing at their responses on their P.E.O.E.s to assess learning.
Most students think that because it is a super bouncy ball that it will bounce taller than my height on the chair, because of what it is made of. It actually only bounces about a third of the original height. Note: gravity is doing the work; I am not exerting any more force--just dropping it. The challenge now is to facilitate learning that helps students build understanding of this phenomenon without giving them the answers.
An important practice for students to develop is asking questions (SP1). Now that they have experienced the bouncy ball demonstration, I give students an opportunity to generate questions that can be investigated or researched to help explain what they saw.
I ask groups of 4-5 students to think of questions that they have and record them in their notebooks.
Some student questions include: Do all balls bounce the same way? Does the initial height affect the height of subsequent bounces?
Once students have their questions recorded, they share them with the class and we record them on the board. Student groups are now responsible for choosing a question to pursue and planning an investigation.
Once students choose their question it is time to plan an investigation. This means that they will apply what they have learned from their scientific inquiry unit, involving IVCDV charts. Additionally, students must create a hypothesis in an If...then statement and a procedure. Once students have created these items it is time to carry out their investigation (SEP 3).
This video gives you an overview of IVCDV charts:
Most students investigate the following:
1) They test different balls by dropping them the same height.
2) They test the effect of dropping the same ball at different heights.
Either way, student ultimately collect evidence that results in them being able to further investigate the outcomes and--most importantly--compare these results with the outcomes from the roller coaster lab to find patterns in their data.
Through the analysis of both data sets, students will confirm what they already know about energy transformations. In that, just like the initial height of a hill on a coaster, their balls respond in similar ways.
In this lesson, students experimented with roller coasters and discovered that the height of the initial hill determines the speed and distance traveled by a marble. They collected observations to support the claim that if the second hill or loop was taller than the initial hill the marble would not successfully make it to the other end of the coaster.
Students were just beginning to develop a conceptual understanding of potential and kinetic energy and transformations. The intention of this lesson is to give students yet another opportunity to deepen their understanding. Remember: NGSS is all about revisiting ideas and building understanding over time, so plan lessons that help students do this in a student-centered environment.
Prior to analyzing results, students create graphs that represent their data. This helps students find patterns in the next part of the lesson.
I begin by having groups of students (preferably the same groups from the roller coaster lab) begin finding patterns in their data. Students work diligently to find patterns. Some common patterns that students find, include:
1) The height of the initial drop affects the height of the second bounce.
2) The balls never bounce as high as the initial hill.
3) Despite the material that comprises the ball, it never bounces as high as the initial hill. However, some balls bounce higher than others.
Now that they have a general analysis completed, I take the opportunity to help students develop conceptual understanding by asking them to compare their results to the roller coaster data. Student quickly realize that the roller coaster and ball labs may entail different tests, yet yield similar quantitative patterns. Here in lies the importance of using Crosscutting Concepts in our classes. They make the process of connecting concepts much easier. The trick, however, is planning lessons that lead to these desirable outcomes without giving students answers.