The ornamental design for education display device, as shown and described.
FIG. 1 is a front perspective view education display device showing my new design;
FIG. 2 is a top view thereof;
FIG. 3 is a right end view thereof;
FIG. 4 is a left end view thereof;
FIG. 5 is a rear view thereof; and
FIG. 6 is a bottom view thereof; and,
FIG. 7 adds detail to the design shown on the upper face of the front view of FIG. 7.
The broken lines shown in the figures are for the purpose of illustrating the environment related to the claimed design and forms no part of the claimed design as to those figures.