The first time I taught: Measuring Speed with Ticker-timers

Lauren has now been teaching physics for five years. Towards the end of her PGCE, she had to teach a lesson on speed. A colleague recommended she use ticker-timers. This is what happened – and how it influenced her subsequent lessons

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This was the plan…

I hadn’t used ticker-timers since I was in school but I felt confident that I could use them to complete a successful practical activity.

My excellent technician set up the equipment for me to practice on before the lesson. I connected the tape, released the trolley, counted the dots and quickly calculated the speed of my object. I left the equipment at the front of my lab ready to demonstrate later.

Next I photocopied my worksheet. It would guide the students through the practical activity, with simple questions such as: “What is the equation for speed?”, “How long is your ramp?” and “How will you calculate an average time?” There was also a quick calculation: “Ticker-timer makes 50 ticks in 1 second, so 1 tick is equal to how many seconds?”

Another teacher had taught the group the speed equation during the previous lesson so I was confident that we would do a quick distance-time graph recap and move onto the ticker-timer practical. Then we’d have a quick plenary in which the students would copy down the homework, make a quick sketch of a velocity-time graph and label.

It was a low ability Year 9 class and, although there were no specific educational needs, the class contained a number of underachieving students. Our SEN department provided extra support in science practical lessons which such classes so I had a teaching assistant to help.

Simple enough.

Here’s how it went…

The starter activities went well – I demonstrated the experiment with my already set up equipment and instructed the students on what they needed to collect.

But then everything started to unravel.

My equipment was in trays, all on one desk. The students piled in, grabbing their kit and bustling back to their tables. But as they began to set it up, we had confusions about where the paper tape was to go. With my lovely equipment already laid out on my desk, it had not occurred to me to check for ticker-timers having nails screwed so tightly they could not be moved or that the paper could be passed through in the wrong direction.

After 20 minutes, only one group had successfully set up their equipment. Meanwhile, several others had screws falling off desks, there was torn up paper everywhere and it was almost impossible to explain to students where they had gone wrong with the racket of 30 ticker-timers beating up and down.

And I discovered that those students who had managed to get dots on the page were struggling with the idea of 50 ticks is 1 second. They didn’t have a stop watch and they could only see faint dots on a piece of paper – how did that help them measure speed?

It must have been my lucky day, because the class were behaving surprisingly well despite the mayhem. Grouping the students together, I abandoned the individual practicals.

We used the two sets of correctly set up equipment to take measurements, with me supervising half of the class and my teaching assistant helping the remaining half. Somehow we made it through the practical, and even managed to work through my deceptively simple worksheet!

The plenary and any idea of multiple results and averages were abandoned.

How I did it the next time…

The following year, I was asked to teach a lesson on measuring speed for an observed lesson. Recalling this experience and anxious to create an engaging and interactive lesson, I abandoned the ticker-timers in favour of a much simpler experiment: “The Fruit Olympics” which involved rolling fruit down a wooden ramp.

The lesson ran much more smoothly: a starter watching Usain Bolt run 100m as several children timed him with stopwatches (allowing for a discussion on reflex time and errors) and a Top Gear clip measuring acceleration in a 0-60mph test.

By the main activity, the students were interested by the fruit basket on my desk. They split into groups and chose two fairly round fruits each. All groups successfully calculated a speed and the competitive Olympics element of the lesson appealed to them.

I felt pleased with this lesson, and although I had abandoned the more traditional ticker tape measurements, the success of the Fruit Olympics allowed me to return to the topic the following week and use ticker-timers then. I am pleased to say that my second attempt at ticker-timers went well, although I still preferred the less noisy fruit rolling.

What I learnt…

Firstly, I realised we can rely on technicians too much. The helpful gesture of setting up my equipment was in fact my downfall. I had not anticipated the students having any difficulty with setting up, it seemed so easy.

From that point forward in my training I made sure to collect individual bits of equipment and practice unfamiliar practicals from start to finish. Although time-consuming at first, it wasn’t long before I had worked out the common issues and eventually the use of new equipment only required a quick chat with another teacher to find out the pitfalls.

A major lesson I learnt moving from my PGCE through NQT and beyond was to have the confidence to be creative in my planning and not to automatically complete practicals in the way “they have always been done”.

Most importantly: never assume that the equipment will work first time or that any big practical activity is simple!

Useful links

The Fruit Olympics lesson plan (Lauren)

Practical Physics: Finding average acceleration with a ticker-timer (IOP/Nuffield Foundation)

Supporting Physics Teaching: Measuring constant speeds (IOP)

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