To express 0.000615 in scientific notation, follow these steps:

1. Move the decimal point to the right until only one non-zero digit remains to the left of the decimal. For 0.000615, move the decimal 4 places to the right, which gives you 6.15.

2. Count how many places you moved the decimal. Since you moved it 4 places to the right, the exponent will be -4 (since you are dealing with a small number, less than 1).

Therefore, 0.000615 in scientific notation is: $6.15 \times 10^{-4}$

Let me know if you'd like further details or clarifications.

Here are 5 related questions you might want to explore:

1. How do you convert a large number, like 54,000, into scientific notation?
2. What are the rules for multiplying numbers in scientific notation?
3. How do you divide numbers written in scientific notation?
4. Why is the exponent negative for small numbers in scientific notation?
5. How do you convert a number in scientific notation back to decimal form?

Tip: When moving the decimal point to convert to scientific notation, count carefully to ensure the correct exponent!