Draw a grid onto the sheet of white poster board. Space the lines every four inches vertically and horizontally, demarcating 4-by-4-inch name tag squares. Use the ruler and a pencil to ensure the lines are straight. Create as many squares as you need to accommodate the number of guests at the conference.
Cut out the squares with a utility knife. Hold the knife against the edge of the ruler placed along the lines.
Punch two holes spaced one inch apart along one edge of each square. Center the holes between the two sides of the square. These holes will later be used to mount the card to the wearer's shirt.
Write the name of the teacher who will be attending the conference in the center of the card in block script. Use capital letters no larger than one inch tall. Orient the card so the two holes are at the top, with the name in the center. Include the first and last name of the participant.
Write the name of the school the teacher works at under his name, followed by the city and state/province. This text can be slightly smaller than the name, if necessary, to fit it on the card.
Open a safety pin and push the clasp end of the pin through the two holes. Close the pin.
Lay out the name cards on a table at the entry to the conference so teachers can find their respective name tags.