The contemporary society has witnessed a dramatic development of education during the past several decades. To coordinate with the tremendous development of education, some people assert that all school teachers should be required to attend courses every five years to update their knowledge. From my perspective, I generally agree with the statement, although it may not be valid enough under certain circumstances.
We shall admit that under some conditions where the knowledge of subjects is relatively stable and does not need to be refreshed continuously, it is unnecessary for teachers to attend courses every five years to update their knowledge. For instance, it is unreasonable to force the teachers who teach sports to participate in courses to refresh their knowledge. Because the types of sports may be constant for a long period, which engenders that teaching sports does not require updating knowledge. Hence, compelling the coaches to attend course for updating knowledge may waste their time which can be used to train their students.
However, never can we neglect the necessity of new knowledge for teachers. Sometimes the experience and methods of education which proved to be efficient under some conditions may not have the same effectiveness under the others, thus the teachers should refresh their knowledge to adapt to the variation of the conditions. Take John Dewey, n outstanding educationist, as an example. He was a strong advocate of the quality education and disdained the examination-oriented education. However, he has changed his opinion after he conducted research in some Asian countries, where he found that the quality education may not be the most effective way to teach. Finally, he acknowledged the advantage of test-oriented education and summarized that the best ideal education concept is combination between quality education and examination-oriented education. Therefore, without updating their knowledge continuously, the teachers cannot be aware of the shortage of their teaching theories and methods which are probably outdated.
In addition, encouraging teachers to take refresher courses regularly can help them get an in-depth understanding of technology-based education. The pervasive use of internet enables students to get access to excellent education online, which may threaten the traditional education. So it is imperative for the teachers to attend courses to update their knowledge when confronting with the competition with online education. For instance, the emergence of Coursera, a website on which people are offered a wide variety of means to assimilate knowledge from the professors of MIT and Stanford, has imposed heavy pressure on the traditional teaching technology. Netizens even advocate that attending regular schools physically is unnecessary. In other words, if teachers are unable to update their interactive skills to fulfill online requests, the dominance held by traditional education tends to be replaced by online niche. Hence, it is crucial for authorities to issue regulations requiring teachers to attend courses periodically to improve professionalism of online education.
To sum up, although the statement is unconvincing under certain conditions, it is still indispensable for teachers to fulfill the requirement of updating professional knowledge by attending courses periodically under most circumstances. 
The contemporary society has witnessed a dramatic development of  
education
 during the past several decades. To coordinate with the tremendous development of  
education
,  
some
  people
 assert that all school  
teachers
 should  
be required
 to  
attend
  courses
 every five years to  
update
 their  
knowledge
. From my perspective, I  
generally
  agree
 with the statement, although it may not be valid  
enough
 under certain circumstances.
We shall admit that under  
some
 conditions where the  
knowledge
 of subjects is  
relatively
 stable and does not need to  
be refreshed
  continuously
, it is unnecessary for  
teachers
 to  
attend
  courses
 every five years to  
update
 their  
knowledge
.  
For instance
, it is unreasonable to force the  
teachers
 who teach sports to participate in  
courses
 to refresh their  
knowledge
.  
Because
 the types of sports may be constant for a long period, which engenders that teaching sports does not require  
updating
  knowledge
.  
Hence
, compelling the coaches to  
attend
  course
 for  
updating
  knowledge
 may waste their time which can be  
used
 to train their students. 
However
, never can we neglect the necessity of new  
knowledge
 for  
teachers
.  
Sometimes
 the experience and methods of  
education
 which proved to be efficient under  
some
 conditions may not have the same effectiveness under the others,  
thus
 the  
teachers
 should refresh their  
knowledge
 to adapt to the variation of the conditions. Take John Dewey, n outstanding educationist, as an example. He was a strong advocate of the quality  
education
 and disdained the examination-oriented  
education
.  
However
, he has  
changed
 his opinion after he conducted research in  
some
 Asian countries, where he found that the quality  
education
 may not be the most effective way to teach.  
Finally
, he acknowledged the advantage of  
test
-oriented  
education
 and summarized that the best ideal  
education
 concept is combination between quality  
education
 and examination-oriented  
education
.  
Therefore
, without  
updating
 their  
knowledge
  continuously
, the  
teachers
 cannot be aware of the shortage of their teaching theories and methods which are  
probably
 outdated. 
In addition
, encouraging  
teachers
 to take refresher  
courses
  regularly
 can  
help
 them  
get
 an in-depth understanding of technology-based  
education
. The pervasive  
use
 of internet enables students to  
get
 access to excellent  
education
  online
, which may threaten the traditional  
education
.  
So
 it is imperative for the  
teachers
 to  
attend
  courses
 to  
update
 their  
knowledge
 when confronting with the competition with  
online
  education
.  
For instance
, the emergence of Coursera, a website on which  
people
  are offered
 a wide variety of means to assimilate  
knowledge
 from the professors of MIT and Stanford, has imposed heavy pressure on the traditional teaching technology. Netizens even advocate that attending regular schools  
physically
 is unnecessary.  
In other words
, if  
teachers
 are unable to  
update
 their interactive  
skills
 to fulfill  
online
 requests, the dominance held by traditional  
education
 tends to  
be replaced
 by  
online
 niche.  
Hence
, it is crucial for authorities to issue regulations requiring  
teachers
 to  
attend
  courses
  periodically
 to  
improve
 professionalism of  
online
 education.
To sum up, although the statement is unconvincing under certain conditions, it is  
still
 indispensable for  
teachers
 to fulfill the requirement of  
updating
 professional  
knowledge
 by attending  
courses
  periodically
 under most circumstances.