01. Introduction
02. Grammar/Activities:
03. Reading Section
04 Listening Section:
05. Speaking Section:
06. Writing Section:
07 Final TOEFL tests

Speaking practice test 1.08

(Question type: Task 4)

You will now listen to part of a lecture. You will then be asked a question about it. After you hear the question, you will have 20 seconds to prepare your response and 60 seconds to speak.

Using points and examples from the talk, describe the double slit experiment and explain why the professor thinks that it is significant.

Preparation time: 20 seconds

Response time: 60 seconds

Text Explanation

This is a difficult lecture! The trick is to realize that you don’t need to understand all of the science behind it. You only need to understand the basic ideas, because you’re going to speak for a shorter time than the professor did: just one minute.

Listen for the intro-detail-detail structure. The professor talks about the experiment and its purpose, first, and then he talks about the results. When he talks about those results, he mentions two important details:

  • The scientists expected the film to show two narrow lines if the electrons were particles.
  • The film actually showed a wave-like pattern.

He explains why the scientists expected that and how the experiment was set up, but it’s most important to hear the difference between the expectations and the results.

Sample notes

  • elect. particles? something else?
    • think small particles
  • 2 slit exprmnt: shoot elect @ screen
  • expect: particles, make lines
    • BUT other: random, wavelike
  • rethink elect.—both particles and waves
    • still today

Sample response #2

The double slit experiment involves shooting electrons through two narrow holes… like, slits… shooting them at a piece of film. When the film is developed, it’s possible to see where each electron landed. The professor thinks that the double slit experiment is significant… uhh… because it shows that electrons have the properties of both waves and particles. Waves create one specific pattern on the screen. But particles…they make two lines. If the electrons behaved totally like particles, then they should have created two narrow bands on the film. It’s important because that’s not what happened, so ideas had to be rethought, and people even talk about the experiment nowadays.