In this demonstration, students will observe the chemical process that occurs when making cheese. Students will be become more familiar with fundamental chemistry terms while making important observations.
This demonstration will help prepare your students to meet the performance expectations in the following standards:
- 5-PS1-4: Conduct an investigation to determine whether the mixing of two or more substances results in new substances.
- Scientific and Engineering Practices:
- Engaging in Argument from Evidence
By the end of this demonstration, students should be able to
- Identify when a change occurs by using observations during a procedure.
- Differentiate between a chemical and a physical change.
- Define various terms that are related to the cheese-making process.
This demonstration supports students’ understanding of
- Chemical reactions
- Chemical Change
- Physical Change
- Acids and Bases
Teacher Preparation: 30 minutes
Lesson: 45 minutes
- Hot plate
- 4 Cups whole milk
- 1 cup buttermilk
- 1/3 cup heavy cream
- Mesh Strainer
- Cheese cloth
- Projector Computer (with internet access), pencils, post-it notes, and Teacher made Graphic Organizer with 3-different boxes for pictures and explanation.
- Always use caution around open flames. Keep flames away from flammable substances.
- Always be aware of an open flame. Do not reach over it, tie back hair, and secure loose clothing.
- Do not consume lab solutions, even if they’re otherwise edible products.
- Food in the lab should be considered a chemical not for consumption.
- This demonstration was originally planned with second graders in mind but could still have a great impact for elementary grades 3-5.
- The teacher will make ricotta cheese while the students observe the process.
- Before explaining what cheese is made of, the teacher will begin by polling the students and asking them a few discussion questions: Do you love cheese? When have you had cheese? Are there different types of cheese?
- Prior to completing the demonstration, it would be helpful for the teacher to familiarize themselves with the background information provided by Science News for Students about the chemistry of cheese.
- The following vocabulary words can be defined in the “Power Words” section of Chemistry Gets Cheesy. These would be helpful for teacher background knowledge and to be able to explain to students during the demonstration depending on their grade/ability level:
- A simple homemade recipe for Ricotta Cheese can be found here. This recipe could easily be cut in half to use fewer ingredients.
- Follow the cheese recipe, and while doing so it would be helpful to integrate the following information:
- Explain that milk is an emulsion, there are tiny fat particles dispersed throughout the watery milk. Milk also contains a combination of water, fat, carbohydrates (sugar), and protein.
- The cheese-making process isn’t simply turning liquid milk into a solid form—this would be a physical change like water freezing to ice. When we make cheese we add an acid (in our case we’re adding buttermilk and cream to the milk) which changes the pH level and helps the liquids turn to solid.
- Adding an acid and then heating is what denatures the protein and causes clumping. This is a chemical change/reaction.
- Make sure the students can see as you scoop the curds from the whey.
- Students shouldn’t eat in the lab. If you would like students to taste it, perhaps you could recommend that they try it at home with a parent, and document the process as an extension.
- Students will complete a Before-During-After chart to organize their observations. The teacher should then compile all observations from students as a class and discuss the process.
- After the demonstration, the teacher could show the students the short video (~ 5 minutes), The Chemistry of Cheese, from the NBC Cheeseburger Chemistry series as a cumulative activity.
- Finally, students can complete the analysis questions (post-video) and share answers as a class.
For the Student
Cheese comes in many different flavors and forms. Today we are going to observe how ricotta cheese is made.
- Wear proper safety gear during chemistry demonstrations. Safety goggles and lab apron are required.
- Watch closely as your teacher makes homemade ricotta cheese.
- Observe the ingredients and processes used.
- Complete the Before, During and After chart with your own drawings and words.
|Before What does the mixture look like at the beginning?||During What do you see happening to the mixture?||After What does the mixture look like now?|
Analysis (complete after watching video)
Determine if the statements are true or false:
- Milk is a very important ingredient in cheese. True or False?
- Milk does not have very much water in it. True or False?
- Making cheese is a physical change. True or False?
- Proteins in milk stick together to form clumps when making cheese. True or False?