Projectiles Launched at an Angle
Lesson 4 of 7
Objective: Students will apply kinematics equations to projectiles launched at an angle.
At this point in the 2-D Kinematics unit, students have already defined and solved problems involving horizontally launched projectiles. So, today's lesson is meant to introduce students to projectiles launched at an angle. The AP Physics 1 Exam includes projectile motion at 3 different points in its curriculum framework, so students need to be familiar with both horizontal and angled launches. The class starts with a ranking activity to assess prior knowledge and then moves into a paired reading activity (SP8). Finally, students get to apply their new knowledge towards the end of class with a second ranking task.
This introduction is meant to gauge students' thinking and help them assess their individual level of understanding. I always have any introductory activity ready to go when students walk into my classroom to help with time management, so this ranking exercise will already be projected onto a screen at the front of the room. I choose not to give students a copy of this task and only project it because I am informally assessing students' prior knowledge. Students know that my expectation for this type of introduction is to write down the problem, their rankings and reasoning, along with their confidence levels, in their science notebooks. This is a great example of what I expect my students' work to look like.
Once the students are settled, I read the instructions to the activity. My reading of the instructions is to ensure students understand that class has started! I emphasize to students that they should work individually and take about 5 minutes to rank the accelerations of the projectiles at their highest point, explain their reasoning, and then assess their level of confidence. During these 5 minutes of work time, I walk around the room and informally assess how students are doing with simple glances at their work. Specifically, I'm looking to see if students recognize that each projectile is accelerated due only to gravity, since that is one of the fundamental concepts of angled projectiles.
When the 5 minutes are over, I am back at the front of the room and ask students to raise their hand if they had a confidence level of 8 or above. This helps me gauge the percentage of my students that feel good about the material we'll be covering today. I make a mental note of those who are confident and use this as a guide to pace today's lesson. At this point, I reveal to the students that each acceleration is the same.
I ask students to line-up in order of their birthday, starting with today (September 8) and moving forward. Once the students are in the proper order, I assign them a partner with the person next to them (the first two people are partners, then the next two, and so on). I've allowed them to choose partners during our last few activities, so I am mixing it up and randomly pairing students today. Once students gather their belongings and get seated at a lab table with their partners, they must take a computer from the cart at the front of the room.
As the computers are booting, I give students a copy of the angled launch reading guide. This document is a guideline that helps students identify the absolute minimum material they should record into their physics notebooks from the Non-Horizontally Launched Projectile section of the Physics Classroom. At this website and still in their pairs, students read through the text and use the document to guide them through the goals of understanding. I let students know that they can read aloud or individually, but the point of them being in pairs is to discuss and determine the most important parts of the text.
While students are working, I walk around with the answer key to ensure they are actively engaged in the learning process. To me, this means that they are on the proper website, reading or discussing some component of projectile motion, and writing down a thorough set of notes. When I walk around, I spot check their written work and engage students in questions such as "What do you notice is the biggest difference between horizontal and angle launched projectiles?" or "What assumptions could we make before that we can no longer make?" Between our informal conversations and my glances at their notes, I feel these informal assessments are adequate in ensuring students are successfully learning.
Unlike in the introduction, I have a printed copy of the closure ranking activity for each student. After each student has received a copy, they get the remainder of the class period to work on their rankings, explanations, and confidence assessments. Students will need to turn in their completed ranking tasks before leaving for the day.
I give the students more time to complete this second ranking task because I hope they can critically think and apply the material learned during the reading activity. In the introduction activity, I made a mental note of the number of students who felt confident in their understanding of angled launches. My point in collecting these closure ranking tasks is two-fold. First, I want to check their answers. Second, I want to count the number of students who had a confidence level of 8 or above. The goal is that students get the correct answers (A/D, C/E, H, B/F/G), and that the number of students who have a high confidence is greater than the number at the start of the class.
My students did a nice job of not only getting the correct answers, but also had a high confidence level. At the start of class only 7% of my students were feeling confident at a level of 8 or above. After reviewing their submitted work, 48% of my students had crossed that threshold of an 8 or high confidence level. While I always hope that more students feel confident about their answers, I did take comfort in that 100% of my students were feeling a confidence level of 6 or higher.