EXHIBIT A --------- Agreement of Joint Filing ------------------------- The undersigned hereby agree that a single Schedule 13G (or any amendment thereto) relating to the Common Stock of Lightspan, Inc. shall be filed on behalf of each of the...

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                                   EXHIBIT A
                                   ---------

                           Agreement of Joint Filing
                           -------------------------

          The undersigned hereby agree that a single Schedule 13G (or any
amendment thereto) relating to the Common Stock of Lightspan, Inc. shall be
filed on behalf of each of the undersigned and that this Agreement shall be
filed as an exhibit to such Schedule 13G.

Date:  February 14, 2001

Entities:  Accel III L.P.
           Accel IV L.P.
           Accel III Associates L.L.C.
           Accel IV Associates L.P.
           Accel Keiretsu L.P.
           Accel Partners & Co., Inc.
           Accel Investors '92 L.P.
           Accel Investors '93 L.P.
           Accel Japan L.P.
           Accel Japan Associates X.X.
           Xxxxxx Family Partnership L.P.      By:  /s/ X. Xxxxxx Sednaoui
                                                 -------------------------
                                                    X. Xxxxxx Sednaoui,
                                                    Attorney-in-fact for the
                                                    above-listed entities

Individuals:  Xxxxx X. Xxxxxx
              Xxxx X. Xxxxx
              Xxxxxx X. Xxxx, III
              Xxxx X. Xxxxxxxxxxxx
              Xxxxxx X. Xxxxxxxxx
              X. Xxxxxx Sednaoui
              Xxxxx X. Xxxxxx
                                               By:  /s/ X. Xxxxxx Sednaoui
                                                 -------------------------
                                                    X. Xxxxxx Sednaoui,
                                                    Attorney-in-fact for the
                                                    above-listed individuals