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Actividad programada por el departamento de Física y Química

 

Percentages and pie charts

The use of % and pie charts in Natural Science. Bilingual 2nd year of ESO
A contribution to the “Proyecto de Mejora de las Matemáticas”. IES José María Pereda. Santander

In the subject “Natural Science”, our pupils in the second year of ESO use some mathematical concepts in English for the first time, because they have Mathematics in the first year, but not in English.
So, the use in Science of some well-known mathematical structures has to be supported by a few previous mathematical explanations, made in English. This is the case of percentages and pie charts, which are the objectives of the two presentations in Power Point that form my contribution to this project.
As in many other cases, we think that only by using these structures in a variety of subjects, we could offer them a clearer understanding of its real meaning.

1) The percentage has proved to be for most students one of the most out-of-reach concepts.

They have formerly heard about and worked with percentages, but our experience shows that they only have a vague idea about how to use them and how to calculate them.
So, the final purpose of this presentation is to improve the use of percentages in Science, particularly in elementary Chemistry, when we work with the composition of matter for the first time.
In the presentation entitled “Percentages”, we allow the students of 2nd year of ESO to revisit the idea of percentage and to use it more accurately as possible in Science.
 

Look at the pdf of this presentation:

 

 

In the next one you can click into it to view the presentation step by step:

 

 

Download the presentation

 

The presentation has two different parts: one specifically devoted to mathematical concepts, and the other, with a few applications to Chemistry.
From slide 2 to 6, a mathematical introduction of percentages is offered, based on tables, used by further explanations. The slides are animated, to use them step-by-step, giving time for students to ask and answer questions.
Slides 7 to 9 contain some examples of percentages that appear in the syllabus of our 2nd- year Natural Science.
a) First example (Slides 7 and 8)
At the beginning of the Chemistry course, the students have to learn the names and symbols of some chemical elements. It is an appropriate moment to start by using percentages.

b) Second example (Slide 9)
In the part of Biology we have firstly to study the composition of the human body:
– The elements, and
– The compounds, with special reference to the amount of water.
It could be another good moment to use percentages.
c) Finally, in the slide 10 there are some explanations and questions about how to transform a fraction into % in problems related to human mass. In the 11th slide, there is an introduction to the idea of pie chart.
 

Activity

 

2) A pie chart is a very clear way to express fractions and percentages, because, at first sight, everyone can interpret the relative proportions shown in it. So, it is one of most common statistical tools we can use.
 

Look at the pdf of this presentation:

 

In the next one you can click into it to view the presentation step by step:

 

Download the presentation

 

In the presentation called “Pie charts”, slides 2 to 4 include some mathematical explanations about the way in which fractions and percentages are connected to pie charts.
A solved example is shown in slide 5. Slides 6 and 7 explain how a % can be transformed into a pie chart, and there is an exercise to apply what they have learnt in the 8th slide.
Some other not-totally-developed examples of exercises in Natural Science are provided in the rest of the slides, the most difficult being those which transform percentages into pie charts.
 

 

Activity

Titles and credits complete both presentations.
Mª del Carmen Urlanga Zubillaga
Departamento de Física y Química
 

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