Miss D has many pairs of shoes in her wardrobe and wants to find out which pair of shoes she can run the fastest in. She chooses three pairs of shoes to try out: high heels, Nike running shoes, and her hiking boots. She will run 425 meters on the same paved running surface, in the same weather conditions, and use the same stop watch for each trial. She will measure the amount of time it takes her to run 425 meters in each pair of shoes. Results:
1. When running in the high heels, it took Miss D 2 minutes and 33 seconds
2. When running in the Nike running shoes, it took Miss D 0 minutes and 45 seconds
3. When running in the hiking boots, it took Miss D 1 minute and 15 seconds

What is the independent variable in this experiment?

1.Weather Conditions

2.Type of shoes worn

3.Time it took to run 425 meters

the answer is type of shoes. The type of shoes is the only thing that SHE controls. The time it took to run 425 meters is something that is controlled by the shoes that she wore, therefore that is the dependent variable. The weather conditions is a constant bc it is kept the same throughout the experiment.

pre-sliced bread is a relatively recent development in baking technology. previous to that, it was always sold in a bakery in daily-made contiguous loaves with no wrapping, and was moderately perishable, usually being used with a day or two (which is why every bakery had a discounted “day-old” bread table.) therefore, pre-sliced bread would grow stale quickly. the hard crust provided a protective layer, and once the exposed dry slice left from the previous cut was removed, the interior was still soft.

what keeps bread soft is the moisture retained in the crumb (the light spongy part that’s not crust). the reason the crust develops is the surface of the dough gets exposed to hot dry air during baking which browns the outer layer and seals it, preventing all the moisture from escaping the dough. longer exposure to air will also eventually cause your bread to lose flavor and become stale.

people were used to cutting slices as they needed them and storing bread in a specially-made wooden or metal breadbox or pail with a lid to preserve it longer, but the first automatically sliced commercial loaves were produced on july 6, 1928, in chillicothe, missouri, using a machine invented by otto rohwedder, an iowa-born, missouri-based jeweler.[1] pre-sliced bread would indeed dry out, were it not for another 20th century technology: the plastic bag. bread could now be pre-sliced, and if the enclosing bag remains sealed as much as possible, the bread will remain soft and fresh for longer than if sitting unwrapped on a shelf or enclosed in a bread box that is not air-tight. sealed packaging meant bread could also be sold on store shelves and eliminate frequent trips to a bakery.

sealing bread in a plastic bag had another effect: the moisture in the loaf will re-distribute into the crust and soften it, which is sometimes more pleasing in a sandwich - especially for children whose teeth might not yet be strong enough to tear through a hard crust. a homemade loaf of bread can be sealed in a bag overnight and the crust will become soft like store-bought sandwich bread.

these were novel changes in how bread was produced and sold, which led to the coining of the phrase “the greatest thing since sliced bread.”