You are given a background paragraph that describes one or more causal or qualitative relationships such as a relationship in economics or a scientific law and a story that makes use of the concepts or the relationship described in the provided paragraph. You need to come up with a question about the story that requires an understanding of the relationship described in the background paragraph. The generated question should not be answerable without both the background and story. Write a question about the story that requires a relationship in the background paragraph to answer. Check whether your question requires both the background paragraph and the story to answer. If your question can be answered by only one of these, try to rewrite your question so that it requires both. Note that "flipping" a word in the question can give rise to a new question where the answer will be different from the original question. Often, "flipping" a word gives rise to flipping the direction of the relationship, for example, from "increase" to "decrease."

Background Paragraph: The first evidence of baking occurred when humans took wild grass grains, soaked them in water, and mixed everything together, mashing it into a kind of slippery and wet broth-like paste.[3] The paste was cooked by pouring it onto a flat, hot rock, resulting in a bread-like substance. Later, when humans mastered fire, the paste was roasted on hot embers, which made bread-making easier, as it could now be made any time fire was created. The world's oldest oven was discovered in Croatia in 2014 dating back 6500 years ago. The Ancient Egyptians baked bread using yeast, which they had previously been using to brew beer.[4] Bread baking began in Ancient Greece around 600 BC, leading to the invention of enclosed ovens.[4] "Ovens and worktables have been discovered in archaeological digs from Turkey (Hacilar) to Palestine (Jericho) and date back to 5600 BC."[5]. 
Story: Students learned about bread making in school, and were fascinated by the history of bread. They learned ancient bread making techniques that they experimented with later on.Group A experimented with Egyptian and Greek techniques, while group B made it the Croatian and the Turkish way.
Which group of students experimented with older bread making techniques?

Background Paragraph: Recall that air pollution is due to chemical substances and particles released into the air mainly by human actions. When most people think of air pollution, they think of the pollution outdoors. But it is just as easy to have indoor air pollution. Your home or school classroom probably doesn't get much fresh air. Sealing up your home reduces heating and cooling costs. But this also causes air pollution to stay trapped indoors. And people today usually spend a majority of their time indoors. So exposure to indoor air pollution can become a significant health risk. 
Story: James spent a lot of time indoors, and didn't get out much like Rob, his friend, who loved outdoors stuff.
Which friend breathes less fresh air on a daily basis?

Background Paragraph: Hydrogen bonds cause water to have a relatively high boiling point of 100°C (212°F). Because of its high boiling point, most water on Earth is in a liquid state rather than in a gaseous state. Water in its liquid state is needed by all living things. Hydrogen bonds also cause water to expand when it freezes. This, in turn, causes ice to have a lower density (mass/volume) than liquid water. The lower density of ice means that it floats on water. For example, in cold climates, ice floats on top of the water in lakes. This allows lake animals such as fish to survive the winter by staying in the water under the ice. 
Story: Marcy is in her kitchen and fills one blue cup with water and then sticks that cup in the freezer. She then takes a green cup and fills that one with water but sets that one out on the kitchen counter. Three hours later, Marcy returns and takes the cup out of the freezer and dumps the now frozen water out onto a plate to look at it and compare it to the water that has been sitting on the kitchen counter.

Has the water in the blue cup expanded more or less than the water in the green cup?