Hello Sabahudin,
Keeping students engaged and curious begins within the first few seconds of them viewing the announcement, discussion, comment, etc....
I use three different tactics to grab the students attention: (1) A colorful large clear font & unique photo applicable to the topic (sometimes gifs are very eye-catching too), (2) My subject line in the topic is either 'funny or controversial', and (3) Within the comment I use links to the information/video and include 'my personal perspective' AND 'open ended questions'.
Because we are constantly bombarded with information, it is important to grab your student's attention from the start -
Lauree Lee Russell