In China students are troubled with English grammar.  For an example：Every verb has different forms that is much complicated to the kids.   The different forms show that the actions take place at different time.  It seems that foreigners describe things more vivid than we do in Chinese. In the language class I explain the phenomenon with the number axis in maths as the following: 

  
As you see, the word ‘do’  changes its out-looking  in different conditions. ​ This reminds the chameleon who can show you special skin colors to match the surroundings at different time. 
I ask the children to make at least five sentences with each verb. 
 It is funny to use maths tool to solve English problem！