Hi there, Ivush!
Besides all the suggestions you already have here above, there are a few more (actually, a lot more) things you can try.
See if any of this helps:
- online exercises (I like ego and englisch-hilfen - to let you compare them, I looked up exercises on the past continuous tense, just as an example - https://www.ego4u.com/en/cram-up/grammar/past-progressive and http://www.englisch-hilfen.de/en/exercises/tenses/past_progressive_statements.htm )
- live chatting (texting) / live conversations with some other students whose mother tongue is different from yours (via Skype, if possible);
- gamification activities (I like www.playdea.com but it is a Brazilian platform, and I don �t know if you can have someone helping you with the Portuguese language around there; if this one doesn �t go, you can look for other free gamification platforms);
- a virtual treasure hunt (each station may be a website / a blog / a file / ..., and to access it, your students may need to crack the code, that is to say, to discover the password that gives them access to a pdf file - which is the next station itself, or where the webaddress to the next station is shown;
- a powerpoint game (a powerpoint presentation in which clicking on the correct answer leads to the next slide; clicking on an incorrect answer sends you straight to the last file where a big "No, try again!" suggests you to click on a button which sends you back to where you were, to take another try - I have a very basic example of one such game on my printables, it �s called "Meet the Clarksons", if you think it may help you visualize what I mean and how it goes);
- dictations (using a Voki character created by you, dictating the text you need it to - students tend to like them a lot; you can access them - for free, by the way - if you register in www.voki.com I have registered there and I like it a lot).
Good luck with your essay!