1. Try a Dictation. Pick a few minutes of the talk to listen to and write down exactly what the speaker says. You can repeat the same section a few times before you check your writing. TED Talks have a transcript of exactly what the speaker said, so you can easily check your work when you are ready.
2. Respond to the Speaker. You can try to do this in writing or orally. TED Talks usually make a claim. Try to agree and support or disagree and debate the claim. It is good practice for your conversation skills. Alternatively, you can test your comprehension by trying to summarize the presentation. In either case, share your ideas with a friend to check your skills.
3. Practice Intonation. The best thing about listening to speakers is you get to hear accurate pronunciation and the rhythm of different statements. Do questions sound different than facts? Does the speaker change how fast he or she speaks? Print out a copy of the transcript to highlight the words he or she stresses or simply stop and repeat phrases to enjoy natural pronunciation.
Finally, even if you don’t attempt any of these activities, listening to TED Talks will expand your vocabulary and your understanding of the world, so it is probably worth trying.