You can click on the maps below to see a larger version.
The map below shows the major highways surrounding Emory and Atlanta. From the north, get to the N Druid Hills exit of I-85 and then drive south on Briarcliff road to N. Decatur Rd. From the south, take the highways to I-20 and then drive east; see the following directions. From the east and west, take I-20 to the Moreland exit. Note that there are two exits for Moreland, you want the one heading north.
Moreland eventually turns into Briarcliff. Take this to N. Decatur Rd., then turn east. You'll drive a short way, til you get to "Emory Village", the campustown area with some shops and restaurants.
Turn left (north) into Emory's campus, as shown on the map below. You can either take a hard left onto Oxford Rd, or a gentle left onto Dowman Drive. Note that Oxford Rd intersects N. Decatur Rd in two places, which you can see on the map below (Oxford curves around).
Park in the Peavine visitor parking lot or the Oxford Road Building parking garage. I think these parking places cost cost $2/hour up to a maximum of $12 and are free on weekends. The Oxford Road Building isn't on my little map, it's between Oxford Road and Dowman Drive, and you'd enter the parking garage off Oxford Road. The building contains a Starbucks as well as a Barnes & Noble store.
The Math/Science Center is on Dowman Drive. Enter right below the "D" in "Drive" on the map, that puts you in the 2nd floor atrium. The Physics Department offices are to your right. Go that direction; when you enter the Physics Dept. area, turn left at the reception desk, turn right at the hallway, and N215 is a a short distance down the hall. To get to room E200, turn left when you enter, it's the big round room. If you enter at the top of the hill, you'll come in on the 3rd floor, and need to go down one level to find N215 or E200. The below picture shows a snapshot of the Math/Science Center. The 2nd floor entrance is at the right side of the picture, and the 3rd floor entrance is at the left side.