Lifelong Learning Programme

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Title of the Experience
Conversion of units of measurement
Name of the teacher
Renzi Alessandra
Country where it took place
School typology
High Secondary School
Thematic Area
Experience typology
Teaching in class
Type of contact
Description of the Experience
The problem I wish to discuss concerns the conversion of units of measurement in Physics. Pupils convert physical quantities using the so-called "equivalence" learned at the secondary school. They use a rule they learned by rote, which allows them to make the count, for example, from cubic metres to cubic millimetres, etc.
There are no problems as long as the memory works and as long as you do not have to multiply or divide units of measurements like km/h or g/cm. Also in this case the students use a conversion formula, and in this way they have always more equivalences to remember and use. I think this is not functional.
I believe that to teach them how to convert units of measurement it is sufficient to explain them that to switch from one unit to another they only need to use multiplications or divisions. So, they would have to do a simple calculation without remembering something.
For instance: I have to go from 3 Km/h to m/s, you have to put in evidence that 3km/h means 3 times 1km divided 1hour
3*km/h = 3*1km/1h
but you know that
1km=1000m, 1h=3600s

3*1km/1h = 3*1000m/3600s = 3*1m/3.6s

Moreover, if I had to convert kg/m^3 in g/cm^3 I will do this calculation
1kg=1000g and 1m=100cm and this implies that (1m)^3=(100cm)^3 and so 1m^3=10^6cm^3

at the end kg/m^3 = (10^3)*g/(10^6)*cm^3 = [10^(-3)]*g/cm^3

In this way you do not need to memorize any formula.

Comments on this Teachers Experience

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Date: 2014.11.06

Posted by Sandis (Latvia)

I have the same problem. Almost all new students converts units knowing facts that in 1 cm is 10 mm and so on. But there are a very large number of complex units of measurement were memory can not help so well. So i teach them same type of transformation as you. At begining is hard. But after couple of lessons they get point.


Dissemination Seminar in Florence

31 October 2015 The seminar has been held in ITIS “A. Meucci” one of the schools involved within Goerudio project activities. Its main aim was to promote the results of the project toward a broad sample of stakeholders even overcrossing the number of people directly involved in the production of project outcomes. This purpose has been totally achieved especially thanks to the participation of students and teachers coming from different schools or from other classes instead of those ones directly involved within the project activities.