Students are able to turn milk into mozzarella cheese in one class period.  This is a great way to demonstrate lactic acid fermentation and the food making process- one of the original biotechnology examples!  Rennet can be purchased online, or you can talk to your local cheese plant to see if they will donate the small amount you will need.  Other ingredients are supplies can easily be purchased in your local grocery store.  

Two lessons and their associated activities explore cellular respiration and population growth in yeasts. Yeast cells are readily obtained and behave predictably, so they are very appropriate to use in middle school classrooms. In the first lesson, students are introduced to yeast respiration through its role in the production of bread and alcoholic beverages. A discussion of the effects of alcohol on the human body is used both as an attention-getting device, and as a means to convey important information at an impressionable age. In the associated activity, students set up a simple way to indirectly observe and quantify the amount of respiration occurring in yeast-molasses cultures. Based on questions that arise from this activity, in the second lesson students work in small groups as they design and execute their own experiments to determine how environmental factors affect yeast population growth.

Students are presented with information that will allow them to recognize that yeasts are unicellular organisms that are useful to humans. In fact, their usefulness is derived from the contrast between the way yeast cells and human cells respire. Specifically, while animal cells derive energy from the combination of oxygen and glucose and produce water and carbon dioxide as by-products, yeasts respire without oxygen. Instead, yeasts break glucose down and produce alcohol and carbon dioxide as their by-products. The lesson is also intended to provoke questions from students about the effects of alcohol on the human body, to which the teacher can provide objective answers.

Biofuels are made from plants that are growing today, and are being considered as an alternative to fossil fuels. To become biofuels, plants need to go through a series of chemical and physical processes that transform the sugars into ethanol. Scientists are interested in seeing how yeast’s ability to transform sugar into fuel is affected by environmental conditions in fields, such as droughts.

This resource has been evaluated using the HQUIM rubric linked here. https://docs.google.com/spreadsheets/d/1y6pUBeJXq-dZLdIjWx_5rNjaj4JCttLpDm5fOt9mNsA/edit?usp=sharing