Choose the best answer to following. Explain your reasoning with one or more complete sentences.
Which of the following best explains why the night sky is dark?
(a) The universe is not infinite in space.
(b) The universe has not always looked the way it looks today.
(c) The distribution of matter in the universe is not uniform on very large scales.

Pablo's friends went on vacation together. Underline the correct pronoun for each sentence.

1. ¿Quieres ir de vacaciones? Yo (te / me) mando el nombre del hotel.
2. Susana no encuentra su peine. Yo (le / los) doy mi peine.
3. Patricia y yo compramos artesanías. (Nos / Te) gustan las artesanías.
4. ¿Sabes hacer surfing? ¿(Me / Te) gusta hacerlo?
5. ¿Me / Le) puedes comprar el bloqueador de sol?

Laura and her friend want to have fun. List related words from the box in the appropriate columns of the table.

Answer the following questions about your life in complete sentences.

1. ¿Te gustaría conocer museos de otros países?

2. ¿Tus amigos dejan el mensaje cuando llaman y tú no estás?

3. ¿Adónde invitas a tus amigos para pasar un rato divertido?

Griselda and Raúl go to fun places. Place and X next to the logical sentences.

1. Griselda prepara la comida en el acuario. ______
2. Raúl y Griselda aprenden mucho en el museo. __________
3. Griselda y sus amigos leen mucho en el parque de diversiones. _______
4. A Griseldale gustan los animales y va mucho al zoológico. ______
5. Raúl compra el boleto de los autitos chocadores. __________
6. Griselda aprende de animales del mar en la vuelta al mundo. ________

Choose the best answer to following. Explain your reasoning with one or more complete sentences.
What is the earliest time from which we observe light in the universe?
(a) a few hundred million years after the Big Bang
(b) a few hundred thousand years after the Big Bang
(c) a few minutes after the Big Bang

Completa la conversación. (Complete the phone conversation.

¿Quieres acompañarme a la feria?

a. ¿Aló?

b. ¡Claro que sí!

c. Tienes una llamada.

Choose the best answer to following. Explain your reasoning with one or more complete sentences.
Which of these pieces of evidence supports the idea that inflation really happened?
(a) the enormous size of the observable universe
(b) the large amount of dark matter in the universe
(c) the apparently “flat” geometry of the universe

Choose the best answer to following. Explain your reasoning with one or more complete sentences.
Which of the following does inflation help to explain?
(a) the origin of hydrogen
(b) the origin of galaxies
(c) the origin of atomic nuclei

Choose the best answer to following. Explain your reasoning with one or more complete sentences.
Which of the following does inflation help to explain?
(a) the uniformity of the cosmic microwave background
(b) the amount of helium in the universe
(c) the temperature of the cosmic microwave background

Choose the best answer for the following question.
When the universe was 380,000 years old, its thermal radiation spectrum consisted mostly of
(a) radio and microwave photons.
(b) visible and infrared photons.
(c) X-ray and ultraviolet photons.

Answer the following questions based on the information provided.
How much cooler is the universe now (at an age of $4\times10^{17}$ s) than it was at an age of 1 second?
a. Its current temperature is one hundred-millionth ($10^{-8}$) the temperature at an age of 1 second.
b. Its current temperature is one hundred-thousandth ($10^{-5}$) the temperature at an age of 1 second.
c. Its current temperature is one-hundredth ($10^{-2}$) the temperature at an age of 1 second.
d. Its current temperature is one ten-billionth ($10^{-10}$) the temperature at an age of 1 second.

What are the four forces that operate in the universe today? Why do we think there were fewer forces operating in the early universe?

Choose the best answer for the following question.
Which of the following does not provide strong evidence for the Big Bang theory?
(a) observations of the cosmic microwave background
(b) observations of the amount of hydrogen in the universe
(c) observations of the ratio of helium to hydrogen in the universe