2.1 Concept Understanding 
Understanding is one's ability to understand or 
understand something. In other words, understanding 
is knowing about something and can see it in various 
aspects. Someone is said to understand something if 
he can provide an explanation and imitate it by using 
his own words. Anderson et al. (2014) stated that 
understanding is defined as constructing the meaning 
of instructional messages, including oral, written, and 
graphic communication. This opinion explains that a 
person is said to understand something if they are able 
to construct the meaning of teaching messages such 
as oral communication, writing, and graphics. A 
person is able to understand a new knowledge when 
he is able to build a relationship between the newly 
integrated knowledge and the cognitive scheme that 
already exists in him.   
Understanding consists of seven types, namely 
interpreting, exemplifying, classifying, summarizing, 
inferring, comparing, and explaining. The seven types 
of understanding are explained as follows: 1) 
Interpreting occurs when students are able to convert 
information from one representation to another. 
Interpretation includes the conversion of words into 
words, images into words, and so on;           2) 
Exemplifying occurs when students are able to 
provide specific examples or examples of general 
concepts or principles. Exemplifying involves finding 
the characteristics of a general concept or principle; 
3) Classifying occurs when students recognize that 
something (a particular instance or event) belongs to 
a particular category (eg concept or principle). 
Classifying includes the discovery of relevant 
characteristics or patterns, which match specific 
examples and concepts or principles;  
 4) Summarizing occurs when students are able to 
propose a single statement that represents the 
presentation of information or a summary of a general 
theme. Summarizing includes the construction of an 
information representation, making a summary, such 
as determining the main theme or topic; 5) Inferring, 
including finding patterns and a series of examples or 
events. Summing up occurs when students are able to 
summarize concepts or principles which consist of a 
series of examples or events through coding the 
relevant characteristics of each event; 
 6) Comparing occurs when students find similarities 
and differences between two or more objects, events, 
problems, or situations; and 7) Explaining occurs 
when students are able to build and use a causal model 
of a system. Models can be derived from formal 
theories, or can be based on research or experience. A 
complete explanation involves constructing a causal 
model, including every major part of the system or 
every major event in a series, and using a model to 
determine changes in one part of the system or 
relationship in a series that affect changes in other 
parts.  
Rosser in Sagala (2014) stated that concepts are 
"an abstraction that represents a class of objects, 
events, activities, or relationships that have the same 
attributes". People experience different stimuli, form 
concepts according to groupings - grouping stimulus 
in a certain way. These concepts are abstractions 
based on experience, and because no two people have 
exactly the same experience, the concepts that people 
form may differ. 
 Klausmeier in Dahar (2011) suggested that there 
are four levels of concept achievement. These levels 
appear in an invariant sequence. People arrive at the 
highest level of achievement at different speeds and 
there are concepts that have never been reached at the 
highest level. Four levels of concept achievement 
according to Klausmeier, namely:                1) Concrete 
level. We can conclude that someone has reached the 
concept at a concrete level if the person knows an 
object that he has faced; 2) Level of identity. At the 
level of identity, a person will recognize an object: (a) 
after a period of time, (b) if the person has a different 
spatial orientation to the object, (c) if the object is 
determined by a different sensory method, for 
example knowing a the ball by touching the ball is not 
by looking at it; 3) Level of classification. At the 
classification level, students recognize the equations 
of two different examples of the same class. Although 
students cannot determine attribute criteria or 
determine words that can represent the concepts, they 
can classify examples and non-concept examples; and 
4) formal level. For concept achievement at a formal 
level, students must be able to determine attributes 
that can limit the concepts. 
According to Asep Jihad and Abdul Haris (2012) 
understanding of concept is a competency 
demonstrated by students in understanding the 
concept and in performing procedures in a flexible, 
accurate, efficient and appropriate manner. Eggen 
and Kauchak (2012) stated that concepts 
understanding can be measured through four ways 
that defining concepts, identifying characteristics of 
concepts, identifying or providing examples of 
concept that have never been before, and connecting 
concepts with other concepts. In this study, indicators 
of concepts understanding were selected as 
explaining concepts, identifying or providing 
examples of concepts, comparing concepts with other 
concepts, and inferring concepts.