Why do formula 1 cars need better
brakes than a normal road car? This
question was the start point to how I taught my students about braking energy
and the key idea that I hung the rest of the lesson on. In terms of teaching, breaking energy was
something new to me, so gave me the opportunity to dip my toe into untested
water and try out a few new ideas. Once
I realised that breaking energy is the same as work done, and that the work
being done by a break must be the same as the kinetic energy of the car, the
structure of the lesson evolves almost by itself.
Pre-Starter
The first thing that students must
get their heads around for the rest of the lesson to make sense is what
breaking energy is and some of the factors that affect the amount of breaking
energy needed to stop an object. Youtube
to the rescue! At times, I think that Youtue
has made me a little lazy, but used sparingly and at the right point in a
lesson, can be very powerful. I found a range
of different clips of different sized cars stopping under different conditions
and start speeds ect and as a class we discussed what effects braking and how
that is related to breaking energy. This
was a important activity as it ensures that everyone in the class is at the
same start point so that no-one is left behind.
I’m not a great lover of how differentiation is crowbarred into lessons,
however, this activity differentiates itself, and allows your higher-level
students to help any lower level students.
Starter
The first equation that students
need to be able to use is how to work out kinetic energy. Historically in my experience this is always
the equation that students seem to get wrong since they type it into their
calculators incorrectly. So, how to force
them to type it in correctly? The only
way that I’ve ever found to help with this is to write the process that they
need to use up on the board, and then go through a few examples with them to
make sure that they’re not missing steps out or trying to be overly clever with
how they’re typing things in. The way
that I always explain to they to type the variables in is as follow; First work
out what velocity times velocity is then press equals, times this by the mass
then press equals, finally times this by 0.5 then press equals. If students follow this methodology every
time they should get the correct answer each time.
Once your student’s have gotten
their heads around using the equation it’s time to give them the opportunity to
have some practice at using the equation for themselves. If you “gamify” the activity, then students
will be happier to work through a series of calculation without moaning that
they’ve just been given a list of equations to work out. The activity that I use is to give students a
6 by 6 board with different variables in each square for them to use to
calculate kinetic energy. I then allow
students to randomly pick questions to answer by rolling a dice twice.
The main part of the lesson
Now that students have been
reminded how to calculate kinetic energy which is arguably the hard part, you
can start to get students thinking about how they can work out breaking
energy. The first step I took was to
connect the main part of the lesson back to the starter by quickly getting
students to calculate the kinetic energy that different F1 cars have when
travelling at different speeds. This
first activity will begin to let students start to build up a mental picture
about what braking energy is in terms of the maths behind it.
The second activity during the
main part of the lesson centres around allowing students to connect the
equations for work done and kinetic energy for themselves. By allowing students to work things out for
themselves it will help them see why the equation works and why breaking force
needs to be calculated how it is.
Depending on the level your class is working at will alter how much help
or guidance they’ll need. Show students
the three equations they need to think about and they let them work through how
to connect them together. Once students
have a single overall equation, allow them to calculate the breaking force
needed by each of the cars travelling to break.
Plenary
Once students have calculated the
breaking force for each velocity you can finish off the lesson with some data
analysis as this will tie everything together and help stretch your higher
ability students. All my plenary
activity asks students to do is quickly draw a graph of velocity the car is
travelling against the breaking energy needed to stop it. After students have a graph drawn you can ask
them to describe what the results show and have a discussion which connects it
back to the start of the lesson.
I hope that these ideas are
different for many others out there and they have provided some inspiration for
things you can do within your own lessons.
You can follow me on twitter @teacherchalky1 or on Facebook
@teachlikeahero , and you can download this lesson from my shop at https://www.tes.com/teaching-resources/shop/chalky1234567
Thanks for reading
D Chalk
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