The goal of this lesson is for students to observe and recognize different types of motion, mainly acceleration and deceleration, and create multiple representations for that motion. I do this lesson after the Motion on an Incline Lab so that students have some exposure to the position vs. time and velocity vs. time graphs for uniform accelerated motion before they look at multiple situations. When students do this activity, they are developing models for accelerated motion in different situations and are communicating that information through graphs and motion maps. I really want students to be working on predicting models and then using those models in future lessons (SP2).
To start out the lesson and the unit, I give students a Unit 2 Learning Target sheet. This target sheet includes all of the learning goals for the students and gives them a list of the things that they should be able to do by the time they finish the unit. I have students rate themselves on the target based on how well they feel they could complete the target. Since we have done this in previous units, I just give a brief reminder that rating themselves as a 1 means that they don't understand at all and rating themselves a 4 means they could teach any other student in the classroom about it. I remind them that it is okay if they are all 1s on the first look at the learning targets because we haven't learned any of this information yet. I ask them to spend a few minutes silently reading the targets and rating themselves as a first look with a shape that we decide on as a class. A student's work for this self-assessment is shown here (Unit 2 First Look at LTs).
After students reflect on the learning targets, I have them turn to the Lab Analysis Notes in their packets. I use this notes page to summarize in a written form what they gathered from the lab in the previous lesson about acceleration and how the motion is represented on position vs. time and velocity vs. time graphs. I explain exactly how I teach the notes in the Lab Analysis Notes Video.
To start out the notes, I discuss the position vs. time graphs and how they look different than the last unit on constant velocity. I show that the slope is changing which tells us that the velocity is changing, so we see the object accelerating. Then I ask them to predict what the position vs. time graph would look like if the incline was greater than in their lab. We discuss how the car would increase its speed faster so the slope would increase faster. Finally we discuss the mathematical model and how we see position = m * time^2.
Then I move to the velocity vs. time graph and I ask them what the graph will look like for both lines, emphasizing that the greater incline will have a greater slope than the smaller incline on the velocity vs. time graph. We complete the mathematical model for each line, recognizing that they models are the same except for the slope. Then I refer them to the generalized model and we find that the model is final velocity = (acceleration x time) + initial velocity.
Finally we at the motion map and I ask them what will happen to the velocity arrows and they respond with "they will get bigger". As we draw the velocity arrows, I ask them if they remember if there was something else we should add based on the video they watched for homework. So we add acceleration arrows to the graph in the same direction because it is speeding up. We then compare the two motion maps to see what affect the incline has on acceleration and see that the velocity arrows get bigger faster and the acceleration arrows are also bigger. By the end of the notes, my students have a page that looks like the Lab Analysis Notes KEY.
After we have discussed the Lab Analysis Guide, I ask students to turn in their packets to the Lab Extension Activity. I show them that there are 7 situations that correspond to the 7 stations in the back of the classroom. Students will see 7 different situations of motion that include a cart on a horizontal track (constant velocity), carts moving up an incline starting at 0 or a positive position (deceleration), carts moving down an incline starting at 0 or a positive position (acceleration), and carts moving up and down and incline starting at 0 or a positive position (deceleration and acceleration). This activity is important because my students have seen one example of acceleration but I want them to be able to see all of the possible situations of an object accelerating or decelerating and associate them with the corresponding graphs. When I set up the tracks, I raise up one side of the track so the it is on an angle (the same at each station) for all of the stations except for the constant velocity station.
I go through what they should write in each section of the page. I tell them that the motion map should go in section 1. I tell them that Section A shows them what they should do with the cart at that station Section B is where they draw the motion map with acceleration and velocity arrows. Section C asks questions about velocity and the velocity arrows and Section D asks questions about acceleration and the acceleration arrows. Section E is the prediction graphing section where they make a guess about what the graphs will look like. Section F is the actual data graphing section where they put the graphs from the computer. Sections G and H ask them about the slopes of the position-time and velocity-time graphs.
When I have shown them where everything is located on the sheet, I tell them that they will start with just the predictions during the first round in Section E. I give them about 4 minutes at each station to observe the motion and predict what all of the graphs will look like. I have them rotate to every station and make predictions before they actual record the graphs from the PASCO equipment. To start, students go to the table number in the back of the classroom that matches the table number they sit at in the front of the classroom.
When students have completed making predictions of all of the stations, I explain how they will fill out the rest of the sections with the information from the motion sensor. I set up the motion sensors with the computer so that they can see a position vs. time graph, velocity vs. time graph and acceleration vs. time graph. Stunts then fill out that data in their lab by copying it directly from the computer. Then I ask them to complete the questions about what is happening to the slope on the position vs. time and velocity vs. time graph and what each slope represents. Finally, I ask them to draw the motion map that represents each situation and to determine if the velocity and acceleration are positive, negative or zero. After providing instructions, I give students 5 minutes to complete one station. Since there is only time to collect data for one station during the class period, they complete a station that they made already made predictions about.
To end class, I have students take a post-it note from the resource bin at the center of the table and gets to chose from the red, yellow or green light. They must complete the sentence starter on the light they choose.
The Red Light: Today my learning stopped because...
The Yellow Light: Today I considered a question, new idea or perspective...
The Green Light: Today I learned __________ because...
When they complete their sentence, they stick the post-it note on whatever light they choose. The stoplight is at the front of the room whenever they finish writing their response to a light.
I do this to get an idea of where students are at in learning the material in a way that they can anonymously express exactly what they are learning or exactly what they are struggling with.