UFOs

What's in the lesson

1. 1Warm-up
2. 2In this lesson
3. 3Guess the words (1)Vocabulary exercise
4. 4Guess the words (2)Vocabulary exercise
5. 5Check the wordsVocabulary
6. 6Check your understandingReading comprehension
7. 7Listen: Erin's lightsListening comprehension
8. 8Use the new wordsVocabulary exercise
9. 9How sure are they?Grammar exercise
10. 10Guessing about the pastGrammar rule
11. 11Choose the best guessGrammar exercise
12. 12Say it naturallySpeaking practice
13. 13Explain the mysterySpeaking practice
14. 14Let's discussDiscussion
15. 15Wrap-up

Homework

1. 1Homework: closest meaningVocabulary exercise
2. 2Homework: your sentencesVocabulary exercise
3. 3Homework: guessing about the pastGrammar exercise
4. 4Homework: a strange eventDiscussion

Words

• sighting/ˈsaɪtɪŋ/

  an occasion when someone sees something unusual or rare

• unidentified/ˌʌnaɪˈdentɪfaɪd/

  not known or not recognized

• hoax/hoʊks/

  a trick that makes people believe something that is not true

• footage/ˈfʊtɪdʒ/

  film or video of an event

• conspiracy theory/kənˈspɪrəsi ˌθiːəri/

  a belief that a secret, powerful group is hiding the truth about something

• skeptical/ˈskeptɪkl/

  not easily believing something without proof

• debris/dəˈbriː/

  broken pieces that are left after something has been destroyed

• classified/ˈklæsɪfaɪd/

  officially secret

• witness/ˈwɪtnəs/

  a person who sees something happen

• rule out/ˌruːl ˈaʊt/

  to decide that something is not possible or not the answer

Two slides from the lesson

Warm-up

Let's talk about mysteries.

1. Have you ever seen something in the sky that you couldn't explain?
2. Do you enjoy movies or shows about aliens? Which ones?
3. Why do you think stories about UFOs are so popular?

Grammar rule

Guessing about the past

modal + have + past participle

How sure?	Positive	Negative
almost certain, from evidence	must have + past participle: The streets are wet. It must have rained.	can't have / couldn't have + past participle: She can't have seen us: she was asleep.
possible	might have / may have / could have + past participle: He might have missed the bus.	might not have / may not have + past participle: They might not have heard the news.

In American English, must not have is also common for a negative conclusion: He must not have heard me (I'm fairly sure he didn't). Don't use can have for a positive guess: say might, may or could have.

could have has two uses. A guess: It could have been a drone (maybe it was). A chance nobody took, as in unit 3: We could have taken the train (but we drove). The context tells you which.