To find the new class size after a 20% increase, you can follow these steps:

1. Calculate the increase in the number of students:
   A 20% increase means that the class size will increase by 20% of the original 30 students.

   $\text{Increase} = \text{Original class size} \times \text{Percentage increase}$ $\text{Increase} = 30 \times 0.20 = 6$

2. Add the increase to the original class size:
   Now, add the increase to the original class size to get the new class size.

   $\text{New class size} = \text{Original class size} + \text{Increase}$ $\text{New class size} = 30 + 6 = 36$

Therefore, the new class size is 36 students.

Would you like more details or have any questions?

Here are 5 related questions that expand on this topic:

1. If the class enrollment increased by 30% instead of 20%, what would the new class size be?
2. What is the percentage increase if the class size changed from 30 to 45 students?
3. If the class size is currently 36 students and decreases by 10%, what will be the new class size?
4. How would you calculate the new class size if the enrollment had been increased by a certain percentage multiple times?
5. If another class started with 50 students and also had a 20% increase, how would the new sizes of both classes compare?

Tip: When calculating percentage changes, always convert the percentage to a decimal (e.g., 20% becomes 0.20) to simplify the multiplication process.