Bagel (and bread) making is a uniquely rewarding activity. Five simple ingredients make up the foundation for any good bagel. Flour, water, yeast, barley malt, and salt—that's it!
Although getting these five ingredients to turn into a bagel is a science, a big perk to each "science experiment" is that you can literally eat your hard work when you are done. This is quite different than say, making spreadsheets or tracking data, which contain neither carbs nor any delicious smells to satisfy you at the end of long day. These seemingly straightforward ingredients, however, can be incredibly temperamental, and one ingredient in particular is undoubtedly the most fascinating and challenging aspect of bagel making.
Yeast is the organism that transforms the “dead” ingredients of flour, water and salt into a towering structure rich with complex flavors and intricate textures. Yeast feeds on sugar and burps out CO2, which causes bubbles to form in the dough—giving it that classic rise and density, and fermenting the dough for the perfect bagel flavor we all know and love. This process is extremely sensitive to factors like temperature, ingredients, and even the air around it, and must be stopped at the exact right time to prevent the dough from over or under rising.
The real work of the baker is to provide the exact environment for the yeast to thrive, stretch the dough so the yeast can make a structure from stronger materials (gluten), and shape it into the form you want. And of course, finally baking it to kill the yeast and stop the process at the exact right time.
If you're having trouble controlling your yeast, try controlling the environment around it to bake consistently good bread each time. What temperature is your water? What temperature do you proof the bread at, and for how long? What is the humidity like in the air when you're baking?
Controlling as many of these factors as possible is the key to understanding which ones are impacting your bread, or your bagels!