Finding the conditions for making curd in Changes around us – Class 6 Science Experiment

Chapter Name: Changes around us

Activity Name: Finding the conditions for making curd in Changes around us

Activity Description:

Required Items:

1. Three empty bowls with lids
2. Ice-cold milk
3. Warm milk
4. Sample curd
5. Stirring utensil

Step by Step Procedure:

1. Take three empty bowls with lids.
2. Add ice-cold milk to bowl 1, and the same quantity of warm milk to bowls 2 and 3.
3. Add a small quantity of curd to bowls 1 and 2.
4. Stir each bowl well, ensuring that the curd mixes with the milk.
5. Cover all three bowls with lids.
6. Keep the bowls in your classroom and ensure they are not touched, even after you leave for home.
7. Leave the bowls undisturbed overnight.
8. When you return to school the next day, observe the changes in the three bowls of milk.

Experiment Observations:

1. Observe the milk in the three bowls and note any changes that have occurred.
2. Determine whether the milk in all three bowls has changed into curd.
3. Compare bowls 1 and 2, and bowls 2 and 3 separately.
4. Answer the following questions based on your observations: a. Why do we notice a change only in bowl 2, even though we added curd to the milk in bowl 1 as well? b. Why do we notice a change in bowl 2, even though we took warm milk in both bowls 2 and 3?

Precautions:

• Ensure that the bowls are tightly covered with lids to prevent contamination.
• Avoid touching or disturbing the bowls during the experiment.
• Use clean utensils for stirring to maintain hygiene.
• Maintain consistent temperatures for the milk in each bowl.

Lesson Learnt from Experiment:

The experiment demonstrates that the addition of sample curd to warm milk is necessary for the milk to change into curd. The warm milk allows the growth of certain bacteria, which facilitates the conversion of milk into curd.

The cold milk, even with the addition of curd, does not undergo the same change. This observation highlights the importance of specific conditions, such as temperature, in the curdling process.

The experiment also hints at the presence of bacteria in curd and introduces the concept of microscopic living organisms, which will be further explored in the lesson “Living Things under the Microscope.”