Problem: Relying on an animal to come by is risky. A flower may have to wait a long time for the right animals to come by. What if one never passes close enough to the flower? Hoping the wind will blow is also risky for a plant. What if the wind does not blow? What if the blowing pollen does not land on another flower? The wind could even blow the pollen over the ocean where it is wasted. Giving free nectar is costly. It is not a good use of the plants energy. A plant uses a lot of energy to produce nectar. Some animals may just drink the nectar. They may not carry off any pollen in return. To improve their chances, plants evolved special traits. For example, they developed ways to hide their nectar. Only certain animals were able to get at the plants hidden nectar. These specific animals might be more likely to visit only flowers of the same species. This was also a benefit for some animals. Animals also evolved special traits to get to the nectar.

Question: "What might some animals do with a plant?"

Answer: "Trample it"

OPTIONS:
- no
- yes
Answer: no

Problem: What if two children push a swing at the same time? Would the swing go higher? Yes, together their force would be more. It is common for forces to be combined. Most objects on Earth have at least two forces acting on them. Do you know what one of them is? Of course, that force is gravity. How many forces do you have on you right now? Gravity pulls you down toward the center of Earth. Your legs exert a downward force. They hold you up against the pull of gravity. Consider the example in Figure 1.3. A book is resting on a table. Gravity pulls the book downward. It has a force of 20 newtons. At the same time, the table pushes the book upward. Its force is also 20 newtons. The table opposes the pull of gravity.

Question: "At what level of force does gravity pull the book downwards?"

Answer: "More than 20 newtons"

OPTIONS:
- no
- yes
Answer: yes

Problem: On a busy Friday morning in Manhattan, nine pedestrians suffered bullet or fragment wounds after police unleashed a hail of gunfire at a man wielding a .45 caliber pistol who had just killed a former co-worker. The officers unloaded 16 rounds in the shadow of the Empire State Building at a disgruntled former apparel designer, killing him after he engaged in a gunbattle with police, authorities said. Three passersby sustained direct gunshot wounds, while the remaining six were hit by fragments, according to New York Police Commissioner Ray Kelly. All injuries were caused by police, he said Saturday. One officer shot nine rounds and another shot seven. Police identified the gunman as Jeffrey Johnson, 58, who was apparently laid off from his job as a designer of women's accessories at Hazan Import Co. last year. Johnson, who served in the U.S. Coast Guard in the mid-1970s, had two rounds left in his pistol. It holds eight, Kelly said. Police identified the slain co-worker as Steven Ercolino, 41, who had apparently filed a prior complaint against his assailant, claiming that he thought Johnson would eventually try to kill him. Both men had filed harassment complaints against each other in April 2011, Kelly added. Ercolino was listed as a vice president of sales at Hazan Import Corp., according to his LinkedIn profile. "It's not something that should happen to a loving person like that," said his brother, Paul. "He's going to be so missed by everybody. He was a light of so many lives."

Question: "How many people were injured?"

Answer: "Nine"

OPTIONS:
- no
- yes
Answer:
yes