Students heat and cool milk, add a starter containing live bacterial cultures, and allow the mixture to incubate in a warm environment. Over several hours, the bacteria ferment lactose into lactic acid, thickening the milk and producing yogurt.

1. Warm 2 pints of milk in a cooking pot over low heat, stirring often, until it reaches about 88°C or just starts to bubble.
2. Place the pot into a bowl of ice water to cool the milk quickly to about 46°C, or until it feels just warm.
3. Pour half a cup of the warm milk into a small bowl and mix in 2 teaspoons of plain yogurt with live cultures.
4. Return this mixture to the main pot and stir thoroughly to combine.
5. Carefully pour the mixture into a clean glass mason jar and screw on the lid.
6. Wrap the jar in a towel and place it in a warm location (e.g., on top of a refrigerator) for 10–12 hours.
7. After incubation, check the yogurt’s thickness and tanginess; longer incubation produces stronger flavor.
8. Refrigerate and enjoy with fruit, honey, or granola. Save 2 teaspoons from this batch to use as starter for the next one.

How to Make Yogurt with Kids - Children's Museum and Theatre of Maine:

📄 How to make homemade yogurt - AUTHOR: https://www.natgeokids.com/au/kids-club/cool-kids/general-kids-club/how-to-make-homemade-yogurt/

• Try different types of milk (whole, skim, plant-based alternatives) and compare texture and taste.
• Test how incubation time affects thickness and tanginess.
• Add fruit or flavorings after incubation for variety.
• Compare results using yogurt starters from different brands.

• Heat milk carefully and stir constantly to prevent scalding.
• Use oven mitts when handling hot pots and jars.
• Keep all containers and utensils clean to avoid contamination.
• Refrigerate yogurt promptly after fermentation and consume within two weeks.

• What role do bacteria play in making yogurt? (They ferment lactose into lactic acid, which curdles milk proteins.)
• Why is it important to cool the milk before adding the live yogurt cultures? (High temperatures could kill the bacteria.)
• How does incubation time affect the yogurt’s taste and texture? (Longer incubation produces thicker, tangier yogurt.)
• Why should new batches of yogurt be started with live cultures from a previous batch? (The live bacteria continue the fermentation process.)