First, the student should check if the salt is already in a 15g container. If it is, then they can simply use that container. If not, then they will need to measure out 15g of salt from the 500g jar. To do this, they will need a scale that is accurate to at least 0.1g. They should also have a container that can hold at least 15g of salt.

Here are the steps that the student should follow:

1. Turn on the scale and zero it out.

2. Place the empty container on the scale.

3. Zero out the scale again.

4. Start adding salt to the container until the scale reads 15g.

5. Once the scale reads 15g, stop adding salt.

6. The salt in the container is now 15g.