Where, When, Why and How
RI.3.7
Read the text, then answer the questions.
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. What would a diagram for this text need to show?
How a Windmill Grinds Flour
A windmill turns moving air into turning stone. The sails are set at a slight angle. Because of that angle, wind pushing on them cannot pass straight through, so it pushes them round instead. The sails turn a horizontal shaft. A large wooden gear on that shaft meshes with a smaller one on an upright shaft, which turns the millstones below. Because the smaller gear has fewer teeth, it spins faster than the sails do. Four turns of the sails can mean twenty turns of the stone. The grain falls between two stones. The top stone turns; the bottom one does not. The grain is crushed between them, and flour comes out at the edge.
- 1. Put these in order: the millstones turn, the sails turn, the gears mesh.
- 2. What would a diagram of a windmill need to label?
LessonPrint · RI.3.7 · Set 24 · free to copy for classroom use