The inhabited history of the Las Vegas Valley stretches to 23,000 b.c. , when much of the area was covered by a prehistoric lake. During this period, the indigenous people lived in caves, hunting the mammals that gathered at the shoreline. The landscape of the valley changed dramatically over the next 200 centuries. The glaciers feeding the lake melted away and the lake evaporated. Fossils tell an obscure story of man's slow and sporadic development. Around 3000 b.c. , native Archaic Indians began to develop a lasting hunting and gathering culture. By this time, the valley was in much the same geographic state as it exists in today, with one exceptionthe presence of artesian springs that bubbled to the surface in several areas. These springs fed a network of streams draining through the Las Vegas Wash to the Colorado River. The areas surrounding the springs were desert oases: sprawling collections of grasses, trees, and wildlife. Many springs lay in areas that would eventually become the center of the modern Las Vegas metropolis. For about 4000 years, the Archaics thrived in a culture that included many signs of early civilization. Signs of even more advancement appeared halfway through the first millennium a.d. , when the Anasazi Indians inhabited the valley. Far more progressive than the Archaics, the Anasazi utilized such formal agricultural techniques as irrigation to assist their harvest. This permitted the Anasazi to achieve a benchmark of advanced societythe ability to live in permanent shelters year-round without need to follow wildlife. Mysteriously, the Anasazi vanished from the valley around a.d.

Question: "What was a difference between the hunting and gathering practices of the Archaics and the Anasazi?"

Answer: "The Arachaics used irrigation to keep animals close by"

Response: no

Tommy and Suzy (brother and sister) went to the playground one afternoon with their mom and dad, Jan and Dean. They were playing a game of tag and having the best time ever running after each other and laughing. They liked to play tag instead of building sandcastles or swinging. They liked tag because they liked to run. They like to play hopscotch or jump rope but that day they wanted to play tag. Other games aren't as fun. They met Tony and Ally (who are best friends) and invited them to play tag too. Tony and Ally like to play other games like hopscotch or jump rope but that day they joined the game of tag. Making new friends is important. Tony and Ally would rather make friends than play their favorite games.

Question: "Who invited Tony and Ally to play tag?"

Answer: "Suzy"

Response: yes

You couldnt survive without your skin. It has many important functions. The main function of the skin is controlling what enters and leaves the body. It prevents the loss of too much water from the body. It also prevents bacteria and other microorganisms from entering the body. The skin helps maintain a constant body temperature. It keeps the body cool in two ways. Sweat from sweat glands in the skin evaporates to cool the body. Blood vessels in the skin dilate, or widen. This action increases blood flow to the body surface. This allows more heat to reach the surface. The heat is then able to radiate off the body. The opposite happens to retain body heat. Blood vessels in the skin constrict, or narrow. This decreases blood flow to the body surface. This reduces the amount of heat that reaches the surface. When this happens, less heat can be lost to the air.

Question: "What are two ways in which the body cools down?"

Answer: "Preventing water loss and constricting blood vessels"

Response: no

The center of an atom is held together by powerful forces. This gives them a huge amount of stored energy. This type of energy is called nuclear energy. This energy can be released and used to do work. This happens in nuclear power plants where they split apart the nucleus of an atom. This splitting apart is called nuclear fission. Another type of nuclear energy happens in the Sun. Here the atoms nuclei are not split apart. Instead, the nuclei of the atoms are fused, or joined together. This process is called nuclear fusion. Some of the suns energy travels to Earth. This energy from nuclear fusion warms the planet and provides the energy for photosynthesis.

Question: "What is the process called when the nuclei of the atoms are fused, or joined together."

Answer: "Photosynthesis"

Response:
no