How to teach students inertial mass using drag racing

Thank you Ofqual for chucking in another term into the new physics content that I have never come across before!  Most other teacher that I spoke to about it knew what inertia is but had not ever used the phrase ‘inertial mass’.  It turns out inertial mass is just a re-arrangement of Newton’s second law.  SO, once I knew that the next conundrum is how to teach it in a way that’s going to keep students engaged.  At this point I must thank old Top Gear which was being repeated on Dave.  For whatever reason they were drag racing and the idea to base this lesson around was born!

Pre-Starter

I am fortunate enough to have a long corridor outside my room, so as the lesson is based around drag racing it would have been criminal not to have used it!  Before students entered the room, I asked them to line up along both sides of the corridor.  At one end I set up a ramp and used four different cars, all different masses.  I asked students to describe what they thought would happen in terms of distance travelled, acceleration and other forces.  We set the cars off down the ramp and saw what happened.  This activity worked well and got students in the correct frame of mind to approach the lesson with.

Starter

As a concept, inertial mass is something that I had never come across, so it’s a safe bet that my students hadn’t.  To help students gain a basic understanding of what inertial mass is and where it comes from I used a tried and tested literacy game.  It’s always important in a lesson to ensure that your students have had to read something as it helps re-enforce expectations and as we all know, the more students read the better their reading age becomes, and the better their reading age the greater progress they are likely to make within their own journey.  I start off by giving students some information on the development of the idea of inertial mass to read.  Depending on the level of your students you could allow them to highlight key points or briefly talk to them before they start of what they need to look out for.  If you have a low ability class, you could almost turn this into a group reading exercise if you have the time.  Once your students have finished reading they can play snakes and ladders.  DO NOT ASSUME ALL STUDENTS KNOW HOW TO PLAY SNAKES AND LADDERS!  After students, have finished make sure that you leave some time to ask specific students answers to some of the key questions to ensure that they have got out of the task what they need.  By running this literacy activity as a game, it almost stops students from putting up any barriers to reading that they may if just given some information to read.

Task 1

Hopefully by now, your students should have some understanding about what inertial mass is, however, I always find that it never does any harm to go over the basics of it again.  This will also allow you to introduce the idea that force in terms of inertial mass is the amount of force it takes to get an object moving.  In this task, I like to get students to manipulate newton’s second law equation using an equation triangle, to construct the equation for inertial mass.  Once students have the equation they will need a chance to do some calculations using it.  You could give students a list of questions to work through which would do the trick but would be very dull.  The way that I like to approach this type of task is to let students work in pairs, rolling a dice to pick which question to answer.  After giving students enough time to have a go at working out three or four, pick specific students to give you the answers to the six questions.  As they give you the answers, note them down on the board as you will be using them in the next task.

Task 2

It’s at this point in the lesson that you bring it back to looking at inertia in relationship to drag racing b carrying out the slowest drag race in history!  Set up the four cars of different masses on a table, and attack a Newton meter to each of them.  Get four students to pull the four cars forward, recording the reading on the Newton meter at the point when the car just started to move.  This will give you a value for the force of each car.  You can then tell students how quickly the cars are accelerating so the inertial mass for each can then be calculated.  This activity is designed to help students see what inertial mass is and will ensure that they have full confidence in using the equation.  This activity will also give the lesson another element which helps keep students engaged in the lesson.

Task 3

Now that students are happy that they can calculate the inertial mass of an object, they can start to look at how inertial mass and force are connected.  Ask students to quickly get down a table with what they worked out earlier in the lesson, and include an extra column for momentum as they will be using it later.  Once students have these results down ask them to sketch a graph of force against inertial mass in their books.  This graph does not have to be precise as students just need to be able to comment on the relationship between these two variables.  If you had a lower ability class, you could sketch the graph on the board and then discuss what it shows as a class.  Students need to be able to explain that as inertial mass increases so does the amount of force required to get an object moving.  Once students can describe the relationship between inertial mass and force, they can start to think about how momentum is related to inertial mass. 

Task 4

Now that your students can work out inertial mass, momentum & have recalled how to work out acceleration I thought that I would take the opportunity to connect them to calculating acceleration from a speed time graph.  Dependent on the level your students are working at you may need to fully explain how to calculate acceleration from a graph again, however with a high ability class you can leave them to it.  After you have explained the task to students I placed six of these questions around the room for students to work through.  By placing the questions around the room, it got students up out of their seats so added another element into the lesson.

Plenary

The type of plenary I used for this lesson was quick and simple.  All I asked the students to do was to describe the inertial mass, momentum and the effect they would have on stopping distance to each other.  First get students into groups of four then give each student a vehicle to talk about.  Give them a bit of time to decide what they are going to say then set them off.  Whilst students are working circulate so you can assess how much they have learnt.

By the end of the lesson I found that my students understood the content and at the same time had a bit of fun.  One word of warning, students may start making car noises at various points during the lesson!

You can follow me on twitter @teacherchalky1 or on Facebook @teachlikeahero. 

Thanks for reading

D Chalk

How to teach Newton's 2nd Law of Motion Using F1

As part of the new Science GCSE, and for the first time that I can remember, Newton’s three laws of motion have to be taught as Newton’s laws.  As a non-physicist, when changes like this happen in the curriculum I find myself filled with dread as it’s unlikely that I’ll have given the content any thought since finishing my GCSEs (which is longer ago than I’m willing to admit).  So, as we move into a new era in Science education I’ve decided not to see new & unknown content as a problem but as an opportunity to improve my teaching practice. 

This story begins on a Sunday afternoon when I was watching the F1, enjoying it however getting a little bored of the same two drivers winning every race.  It got me thinking about how could I teach using formula 1 and hopefully make it more interesting than this race?  So, when I came to the point where I had to teach acceleration this year I realised that my time had come.  That evening I reminded myself what Newton’s 3 laws of motion are and set out planning Newton’s 2nd law on acceleration using F1.

The Pre-Starter

It’s at this point of the lesson when you have one chance to convince your student’s that they want to engage with the lesson and use calculations.  In the past I’ve always had students that have moaned about having to do maths outside of a maths lesson, however I’ve found that grabbing them straight away and introducing one of the equations that they will need to be able to calculate answers with by using something like racing works really well.  The way that my pre-starter works is by drawing a race track over a few tables, then as a class, get students to use the basic equation for acceleration to do a series of calculations around the track.  The main stumbling point of this activity is making sure that all students have a calculator handy, however, if your school allows it phones have calculators on and the majority of students will have one of them.  After this activity student’s should have a basic understanding about what the lesson is going to be about and it really sets the scene for all of the other tasks they are going to work through.

Starter

The starter activity leads straight on from the pre-starter, so hopefully as students have just worked through something similar they should have no problem working through it.  Before setting students off briefly on the board, explain to students how to calculate basic acceleration again using the correct equation.  Using the table off the board, get students to calculate the acceleration of the car in each section using the information from their race track diagram.  By working through this activity students will have a range of acceleration values to use during the next part of the lesson when they have to calculate the force of the car in each sector.

Task 1

The first task in the main part of the lesson continues to focus on calculating acceleration, but this time from graphs.  Students should have already have developed this skill previously in the calculating basic acceleration lesson, however, they will need this skill re-enforcing so this is the ideal opportunity to do this.  Start this task of by reminding students how to calculate acceleration from a graph by working out the change in speed & the time taken from it.  They can then use the acceleration calculation to work out the acceleration shown in different sections of the graph.  After your student’s have had the task explained to them place a series of graphs around the room for students to work through.  This will primarily enable students to become more confident with this way of calculating acceleration, and will get students up and moving around to ensure that they don’t feel like they’re just sat down working through equations.

Task 2

Now your students have been reminded how to calculate acceleration, it’s time to finally tattle Newton’s 2nd law.   The first thing you really need to do is explain to students what it is and then how it is calculated.  At this point I re-engaged the students by relating it back to F1 and showed students a few youtube clips which as a class we calculated the force of different F1 cars from.  This first part of the task played 2 roles in that it gives the lesson another element which helps students engage and it gives them a chance to use the equation in a low risk way as they will be using it as a class.  The task finishes off with students going back to the starter activity and using the mass of a F1 car, to calculate its force in each sector of a race track.

Task 3

Now that students can use Newton’s 2nd law they need to manipulate it especially as in a few lessons they will need to use this equation to describe inertial mass.  This task starts with as a class asking students to rearrange the equation using an equation triangle.  The way that I stepped this task up to start off with is to give students mini white boards to rearrange the equation on before holding them up to assess how many of them had done it correctly.  The second part of this task lets students pick a series of questions to answer using their rearrange equation using a dice.  This gamifies the task giving students the impression that they are playing a game rather than using a calculation, and gives the lesson a different dimension as we move towards the plenary activity.

Plenary

To finish this lesson off I, like to use a task that not only pulls together what students have covered in this lesson, but brings together many concepts they have covered over the last few lessons.  It starts off by giving students a time distance graph that they can use to calculate speed at different points.  Once they’ve worked out the speed they can calculate the acceleration at different points.  Finally using the mass of a F1 car students can calculate the force of the car at different points on the graph.  This activity will not only enable you to assess how much students have taken from this lesson, but will also let you assess how well students have done over time.

By the end of the lesson I found that my students understood the content and at the same time had a bit of fun. 

You can follow me on twitter @teacherchalky1 or on Facebook @teachlikeahero 

Thanks for reading

D Chalk