Lifelong Learning Programme

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Title of the Experience
Gross weight, net weight & tara Experimentarium
Name of the teacher
Aleksandar Angelov (center for creative education)
Country where it took place
School typology
Primary school
Thematic Area
Maths, Science
Experience typology
Teaching in class
Type of contact
Description of the Experience
Key competences
communication in the mother toungue, mathematical competence
learning to learn.

School subjects/ areas
interdisciplinar activity: maths, science, motherlanguage.

the classroom

1 hour lesson

exercise book, text book, balance, weights, different kind of objects

Activity description
The activity starts with a brainstorming, to understand what students
know on the topic.
Put on the balance a box of crayons and weigh it.
Put on the balance crayons, alone.
Write on the blackboard weights and ask pupils to discover the weight of
the box (tara).
Encourage students discovering the rule.
Find other objects to make students reinforcing the knowledge.
Teacher suggestions

Questions are the starting point, to:
- motivate and interest the students;
- make the students reflect and observe;
- raise hypotheses and links.
Ask students to reflect on the meaning of the words “gross weight”, “net
weight” and “tare weight” to see if someone could explain them.
Go to the operative phase, in which is necessary to show what “gross
weight”, “net weight” and “tare weight” are and which are their
Bring a weight scale and weight first a tin of felt-tip pens – (f.i.260
grammes) –, then only felt-tip pens – (f.i.230 grammes) – and finally the
empty tin – (f.i.30 grammes) –. Write the gathered data on the
blackboard (using the same unit of measure, to simplify the observations)
and ask students for their observations.
Ask pupils to represent with a diagram what they can observe.
In order to reinforce and simplify the other two formulas referring to the
same topic, I propose other practical situations f.i. one with a box of
apples, the other one with a box of chocolates.
Give tables to complete and simple problems to solve, where gross
weight, net weight and tare weight have to be found.
In a second moment, give them more difficult problems, giving the weight
data in two different units of measure, to stimulate students to use
equivalences before doing operations.

Comments on this Teachers Experience

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Date: 2014.11.06

Posted by Bogusława Szukalska (Poland)

It is important to get students attention to understand the relationship between the units used in practice and to experience it. I usually take my students to shops and allow students for self- testing, so that they can freely refer to the different types of terms with which they may encounter in everyday life as well as when solving mathematical tasks. Such dependencies can be analyzed when shopping at grocery. At the store we can find out in what units we buy a product, what is the relationship between quality, price, value, and terms of gross, net, tare. This exercise you proposed is very good for classes.


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.