This research aims to study and classify errors in polynomials made by
secondary school students. The data for error identification was collected
from exercise books of 72 eighth grade students. Three types of errors were
examined: careless, computational, and conceptual errors. The errors were
considered according to four topics in polynomials: similar terms of
monomials; addition of polynomials; subtraction of polynomials; and
multiplication of polynomials. It is found that students made the highest
computational errors in identifying monomials’ similarity, which accounts
for 17.86%. They have the highest percentage of making computational
errors in the addition and subtraction of polynomials, which account for
10.88% and 12.04%, respectively. Lastly, they have the highest percentage
of making careless errors in the multiplication of polynomials, which
accounts for 14.44%. Furthermore, it can be seen that the source of errors is
learners’ carelessness when writing the question and its answer. In addition, the basic knowledge of computing addition, subtraction, and multiplication of integers, is the most crucial factor that leads to incorrect answers. Nevertheless, most students understand