Wordwall is a website where you can play online games with your students, either in solo or in teams. It is one of my favourites due to its versatility and wide variety of games. Students can learn vocabulary or revisit their background knowledge while having fun. Another extra point: students forget they are in a real class!
An activity could be a speaking roulette: it is suitable for the beginning of the lesson, where students can break the ice as they practise vocabulary on the relevant topic.
This is a great source of worksheets to be sent as homework or extra practice during the lesson. On this platform, students can work on different types of activities (mostly based on grammar points) and receive self-assessment: they can check the answers on their own or send the worksheet directly to the teacher, who will be able to see the total score obtained by the student. It is a good option for those students who need further practice on a topic.
Padlet is a website where students can work collaboratively on the same presentation. They can create beautiful boards to collect, organize, and present anything.
A possible activity is to create mindmaps on, for example, vocabulary. Students will have to work collaboratively to add words, expressions and idioms related to the topic using real-life examples.