There are different types of non-probability sampling methods. Below are examples of such methods. You are required to go through them and (for each example); 

a. Name the Sample Method b. Write a not in its possible strengths & weaknesses 

Example (1) A researcher wants to find what people think about a new canned juice that has currently been produced. To ensure that all sections of the population are present in his research sample, he investigates what characteristics are important (e.g. age, gender, nationality), then, how many people should be samples from each of these categories. So he stands in the street and selects people that match each category, till the aimed number within each category is reached/completed.  

Example (2) A researcher wants to search ‘drifting’ in Muscat. One way to conduct this research is by asking those who are doing ‘drifting’. By personal contact, he could come across a person who likes to do drifting almost on a weekly basis. The research was able to talk to this person, establish a good relationship and gain some useful information. This person recommended a friend who was also willing to talk to the researcher. This endures with one person recommending another and on and on, till the researcher had interviewed 20 different people. 

Example (3) A researcher was interested to search students’ opinions regarding the recreational facilities within their college campus. She stood by the entrance to the college student union open hall and stopped students passing from there, asking them a list of questions about the college recreational facilities. She did this until she reached 100 students.    

Example (4) A researcher wants to search the effect of a family's financial support on their life. As he experienced this within his family, and as he had come across others in a similar position, the researcher selects whom to interview based on his existing knowledge of who would be suitable to become a participant in research.