North, South, or Middle?
Lesson 7 of 10
Objective: SWBAT discover that the poles of the magnet are stronger than the middle of the magnet.
Setting the Stage
Advanced Preparation: bar magnets, paperclips
This activity will allow the students to do a quick investigation that has them using the scientific method. They will make a prediction about the strength of different areas of a magnet and then test their prediction by seeing how many paperclips each section can hold. The students will have to record their results on a table and then draw a conclusion about their results. The lesson will end with the students designing magnetic cranes that can lift a car.
NOTE: Our district is transitioning to the NGSS. Although we are implementing some of the units this year, I am still required to teach units that have now been assigned to other grade levels. This unit is one of those units that has been affected by the shifts in grade levels. I continue to teach this unit because it meets the following Vermont State Standards:
S1-2:2 Students demonstrate their understanding of predicting and hypothesizing
S1-2:3 Students demonstrate their understanding of experimental design
S1-2:4 Students demonstrate their ability to conduct experiments
S1-2:6 Students demonstrate their ability to analyze data
This investigation also addresses the NSES expectation of students understanding that magnets attract certain types of materials.
I want students to gain a sound and working understanding of the scientific method. Although this unit will bring in magnetic concepts, the "major focus" continues to be developing learners to think like scientists through experimental learning.
I start by having the students gather on the carpet. I have them face the whiteboard for this part of the lesson. Before the discussion, I draw a big bar and horseshoe magnet on the board and label the poles north and south.
"What did I draw on the board? What does the N and S stand for? Today you are going to find the strongest part of a magnet. You will have to decide if it is the north pole, the middle, or the south pole."
I am choosing to start the lesson with this to make sure students are clear on the poles and the middle of the magnet. They must understand this before they can conduct the investigation.
"How do you think we could test the strength?"
I ask them this question just to get them thinking and I want to see if any students come up with the idea of testing the magnets ability to lift something. At the end of the lesson, I will be asking the students to draw a diagram of a magnet crane that can lift a car. I relate that task with the ideas that may come up with this question.
Advance Preparation: You will need to make a Magnet Strength Recording Sheet for each student in your class.
The students are now going to work in teams to test the different sections of a bar magnet. You will need a bounty of paperclips for this part of the lesson.
"You are now going to work in teams of two (three if you have an odd amount of students) and test the strength of the poles and middle of a bar magnet. You will test how many paperclips the poles and the middle can hold at one time. It is important that you test each section individually. In other words, don't test all three sections at the same time. You will add one paperclip at a time, making a paperclip chain as you test. As you go to add a paperclip, you can pull the chain off the magnet, add the clip, and then test the magnet again."
"Before you start, I want each of you to read the question and Make A Prediction about the magnet. You can write your prediction on the line (next to the word prediction)."
I want to have the students do this before they get the materials and start testing, this way they won't forget. Students tend to get excited about this test and the idea of building long chains and seeing the strength of the magnet. I also go over the table and the categories to make sure that they are clear on how they are recording their results.
"Once you have tested each section, I want you to answer the question at the bottom of the page. This is your conclusion."
I gather the students back on the carpet for a quick science circle discussion. The goal of this discussion is for the students to realize that the poles of the magnet are the strongest. However, I don't want to just state it or ask what each students' results were. Instead I engage them in a conversation where they come to the conclusion as a group.
"I would like to talk about your tests today. Who would like to start?"
I continue to moderate the conversation and get as many involved in the conversation as I can.
"Before we end today's lesson, I want to go back to the question I first asked you. How can we test a magnets strength? Some of you talked about having it pick up things (if this was mentioned, if not skip this line and use the next line). We just tested the strength of a magnet by picking up paper clips."
"You must now use what you just learned about the poles of the magnets and its strengths and design a crane that can pick up a car. As the designer of this crane, you are allowed to use four super strong bar magnets. You must label your crane and illustrate to me where the magnets are located and explain why you chose to position the magnets the way you did. "
I may need to have them finish this during another time. I don't want to rush them and I also want to make sure that they are clear and elaborate with their resigning.
I look through the students recording sheets to see how well they did with filling out the table. I meet with any students who have trouble with this. However, I spend a lot of time in math and science with tables and feel that most won't struggle with this.
I also look at their crane designs. If any students didn't place the magnets with the poles as the attraction point,I meet with them and review the results of their experiment and relate it to the design of the carne.