There are 240 students in the seventh grade, and 10% are in the Environmental Club. How many students are in the Environmental Club?

To find out how many students are in the Environmental Club, we can calculate 10% of the total number of students.

First, we calculate 10% of 240:

\[ 10% \text{ of } 240 = \frac{10}{100} \times 240 \]

This simplifies to:

\[ = 0.1 \times 240 \]

Calculating this gives:

\[ = 24 \]

Thus, the number of students in the Environmental Club is \( \boxed{24} \).