MID for method in lang teaching

my love & my best for my beloved class

My name is Fauzan. I am a new English teacher. I feel happy to be a teacher in my SMP class because in this school I teach English while increasing my English speaking. My school locate in a small island   surrounded with the beautiful views of beach and traditional sasak houses. Every day it is always crowded by the foreigner  who come for recreation. All of my students can speak English well. In the class I explain the material in English orally and all of my students understand me easily. Now I am confuse after giving them a written quiz because all of their score are poor. It is far from my prediction. Most of their answers are  wrong in written and grammar. They  are wrong to write English words and it difficult for me to understand what they mean. Really.... I need the readers help to solve my confused.............. 

1. What is the effective assumption or approach to solve his teaching problem? 
2. What is the match method in that situation to use?
3. State a technique and create a scenario to teach in his class to help him solve the problem?
4. Sent your help to the following email:  Your name and class as the tittle of your email entry oesnoedotuu@gmail.com