Following a Technical Explanation
RI.3.10
Read the text, then answer the questions.
How a Canal Lock Works
A canal cannot run uphill. Where the land rises, engineers build a lock: a chamber with a gate at each end. A boat going uphill enters the lock through the lower gate. The gate closes behind it. Sluices in the upper gate are opened. Water flows in from the higher stretch of canal, and the boat rises with it. No pump is needed, because the water comes down by gravity. When the water inside matches the level above, the upper gate can be opened and the boat moves on. Going downhill, everything runs the other way: the water is let out, and the boat sinks with it.
- 1. Why must the lower gate be closed before the sluices are opened?
- 2. Explain the cause and effect between the sluices and the boat.
- 3. Put these in order: the upper gate opens, the lower gate closes, the sluices open.
Why Bread Rises
Yeast is alive. It is a fungus, and each grain of dried yeast holds millions of cells waiting for water. Add warm water and the cells wake up. They begin to feed on the sugars in the flour. As they feed, they give off carbon dioxide gas. The gas cannot escape, because kneading the dough has built a stretchy web of gluten that traps it. Thousands of tiny bubbles form, and the dough swells. In the oven, two things happen. The trapped gas expands in the heat, so the loaf rises further. Then the heat kills the yeast and sets the gluten, and the bubbles are locked in place. That is why bread has holes in it.
- 1. Put these in order: the gluten sets, the yeast feeds, the gas expands.
- 2. Explain the cause and effect between kneading and the holes in bread.
- 3. What would happen to dough with no gluten in it?
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