Solving
Problems with The Percentage Bar
By
; Frans van Galen and Dolly van Eerde
Many students
in junior school know about percentage, but yet they often struggle with
percentage problems. When they got this problem :
On a bike
that normally cost €600 you get a discount of 15%. What do you have to pay?
Surprisingly
for 14 tested students, only some students who solve that question correctly.
The researcher found that 8 of 14 students written 600 divided by15, the
original price divided by the discount percentage. This problem seems to be a
standard percentage problem, so how can it be that children in 7 grade still
struggle with such a simple problem?
Based on
that problem, the researcher tried to introduce percentage bar to solve that
problem. When students try to solve percentage problems, drawing a percentage
bar has several advantages (van den Heuvel, 2003; van Galen et al,2008;
Rianasari et al,2012). First, students can make representation of themselves of
the relations between what is given and what is asked.
And the third advantage is that
percentage bar offer a natural entry to calculating via 1%.
From all the
figure, showed that percentage bar more meaningful because it gives clear and
concrete picture of the relations between the total and its parts.
Reference
Janssen,
J., F. Van der Schoot & B. Hemker (2005). Balans [32] van het Reken Wiskundeonderwijs aan het Einde ven de
Basisschool 4; Uitkomsten van de Vierde Peiling in 2004. Arnhem: Cito.
Rianasari,
V.F., I. K. Budasaya & S. M. Patahuddin (2012). Supporting Students’
Understanding of Precentage, IndoMS. Journal
on Mathematics Education, 3(1), 29-40.
Van
den Heuvel-Panhuizen, M. (2003). The didactical use of models in Realistic
Mathematics Education: An example from a longitudinal trajectory on Precentage.
Educational Studies in Mathematics, 54(1),
9-35.
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