OFFER TO PURCHASE FOR CASH
                     ALL OUTSTANDING SHARES OF COMMON STOCK
           (INCLUDING THE ASSOCIATED PREFERRED STOCK PURCHASE RIGHTS)
                                       OF
                        NATIONAL COMPUTER SYSTEMS, INC.
                                       AT
                              $73.00 NET PER SHARE
                                       BY
                        PN ACQUISITION SUBSIDIARY INC.,
                     A WHOLLY OWNED INDIRECT SUBSIDIARY OF
                                  PEARSON PLC
- ------------------------------------------------------------
  THE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE AT 12:00 MIDNIGHT, NEW YORK CITY
      TIME, ON THURSDAY, SEPTEMBER 7, 2000, UNLESS THE OFFER IS EXTENDED.
- --------------------------------------------------------------------------------

                                                                  August 7, 2000

To Our Clients:

    Enclosed for your consideration is an Offer to Purchase dated August 7, 2000
(the "Offer to Purchase"), and the related Letter of Transmittal (which,
together with amendments or supplements thereto, collectively constitute the
"Offer") relating to the Offer by PN Acquisition Subsidiary Inc., a Minnesota
corporation ("Purchaser") and a wholly owned indirect subsidiary of Pearson plc,
a public limited company registered in England and Wales ("Parent"), to purchase
all outstanding shares of common stock, par value $0.03 per share (the "Common
Stock") including the associated preferred stock purchase rights (the "Rights"
and together with the Common Stock, the "Shares"), of National Computer
Systems, Inc., a Minnesota corporation (the "Company"), upon the terms and
subject to the conditions set forth in the Offer. Also enclosed is the Letter to
Shareholders of the Company from the Chairman of the Board and Chief Executive
Officer of the Company accompanied by the Company's Solicitation/Recommendation
Statement on Schedule 14D-9.

    We (or our nominees) are the holder of record of Shares held by us for your
account. A tender of such Shares can be made only by us as the holder of record
and pursuant to your instructions. The Letter of Transmittal is furnished to you
for your information only and cannot be used to tender Shares held by us for
your account.

    We request instructions as to whether you wish to tender any of or all the
Shares held by us for your account pursuant to the terms and conditions set
forth in the Offer.

    Your attention is directed to the following:

        1. The offer price is $73.00 per Share net to the seller in cash,
    without interest thereon, upon the terms and subject to the conditions of
    the Offer.

        2. The Offer is being made for all outstanding Shares.

        3. The Board of Directors of the Company (at a meeting duly called and
    held) has (i) determined that the Merger Agreement (as defined below), the
    Offer and the Merger (as defined below) are fair to and in the best
    interests of the Company and the shareholders of the Company, (ii) approved
    and adopted the Merger Agreement and the transactions contemplated by the
    Merger Agreement, including the Offer and the Merger and (iii) resolved to
    recommend that shareholders of the Company accept the Offer and tender their
    Shares pursuant to the Offer. A committee of the Board of Directors of the
    Company, formed pursuant to Section 302A.673 of the Minnesota Business
    Corporation Act (at a meeting duly called and held) has approved the Merger
    Agreement and the transactions contemplated by the Merger Agreement,
    including the Offer and the Merger.

        4. The Offer is being made pursuant to the Agreement and Plan of Merger,
    dated as of July 30, 2000, among Parent, the Purchaser and the Company as
    amended by Amendment No. 1 to Agreement and Plan of Merger, dated as of
    August 4, 2000, among Parent, the Purchaser and the Company (as so amended,
    the "Merger Agreement") pursuant to which, as soon as practicable following
    the consummation of the Offer and the satisfaction or waiver of certain
    conditions, the Purchaser will be merged with and into the Company with the
    Company surviving the merger as a wholly owned indirect subsidiary of Parent
    (the "Merger"). At the effective time of the Merger, each outstanding Share
    (other than Shares owned by Parent or the Purchaser or by shareholders, if
    any, who are entitled to and properly exercise dissenters' rights under
    Minnesota law) will be converted into the right to receive the price per
    Share paid pursuant to the Offer in cash, without interest, as set forth in
    the Merger Agreement and described in the Offer to Purchase. The Merger
    Agreement provides that the Purchaser may assign any or all of its rights
    and obligations (including the right to purchase Shares in the Offer) to
    Parent or any direct or indirect wholly owned subsidiary of Parent, but no
    such assignment shall relieve the Purchaser of its obligations under the
    Merger Agreement.

        5. THE OFFER AND WITHDRAWAL RIGHTS EXPIRE AT 12:00 MIDNIGHT, NEW YORK
    CITY TIME, ON THURSDAY, SEPTEMBER 7, 2000 (THE "EXPIRATION DATE"), UNLESS
    THE OFFER IS EXTENDED BY THE PURCHASER, IN WHICH EVENT THE TERM "EXPIRATION
    DATE" SHALL MEAN THE LATEST TIME AT WHICH THE OFFER, AS SO EXTENDED BY THE
    PURCHASER, WILL EXPIRE.

        6. The Offer is conditioned upon, among other things, (a) there being
    validly tendered and not validly withdrawn prior to the Expiration Date that
    number of Shares that would represent at least a majority of the Fully
    Diluted Shares (as defined in Section 14 of the Offer to Purchase) on the
    date of purchase, and (b) any waiting period under the Hart-Scott-Rodino
    Antitrust Improvements Act of 1976, as amended, applicable to the purchase
    of Shares pursuant to the Offer or to the Merger and any other waiting
    periods under any other applicable material competition, merger, control,
    antitrust or similar law or regulation shall have expired or been
    terminated.

        7. Any stock transfer taxes applicable to a sale of Shares to the
    Purchaser will be borne by the Purchaser, except as otherwise provided in
    Instruction 6 of the Letter of Transmittal.

        8. Tendering shareholders will not be obligated to pay brokerage fees or
    commissions to the Dealer Manager, the Depositary or the Information Agent
    or, except as set forth in Instruction 6 of the Letter of Transmittal,
    transfer taxes on the purchase of Shares by the Purchaser pursuant to the
    Offer. However, federal income tax backup withholding at a rate of 31% may
    be required, unless an exemption is provided or unless the required taxpayer
    identification information is provided. See Instruction 9 of the Letter of
    Transmittal.

    Your instructions to us should be forwarded promptly to permit us to submit
a tender on your behalf prior to the Expiration Date.

    If you wish to have us tender any of or all the Shares held by us for your
account, please so instruct us by completing, executing, detaching and returning
to us the instruction form on the detachable part hereof. An envelope to return
your instructions to us is enclosed. If you authorize the tender of your Shares,
all such Shares will be tendered unless otherwise specified on the detachable
part hereof. YOUR INSTRUCTIONS SHOULD BE FORWARDED TO US IN AMPLE TIME TO PERMIT
US TO SUBMIT A TENDER ON YOUR BEHALF PRIOR TO THE EXPIRATION DATE.

    Payment for Shares accepted for payment pursuant to the Offer will in all
cases be made only after timely receipt by ChaseMellon Shareholder Services,
L.L.C. (the "Depositary") of (a) certificates for (or a timely Book-Entry
Confirmation (as defined in the Offer to Purchase)) with respect to such Shares,
(b) a Letter of Transmittal (or a facsimile thereof), properly completed and
duly executed, with any required signature guarantees, or, in the case of a
book-entry transfer effected pursuant to the procedures set

                                       2

forth in Section 2 of the Offer to Purchase, an Agent's Message, and (c) any
other documents required by the Letter of Transmittal. Accordingly, tendering
shareholders may be paid at different times depending upon when certificates for
Shares or Book-Entry Confirmations with respect to Shares are actually received
by the Depositary. UNDER NO CIRCUMSTANCES WILL INTEREST BE PAID ON THE PURCHASE
PRICE OF THE SHARES TO BE PAID BY THE PURCHASER, REGARDLESS OF ANY EXTENSION OF
THE OFFER OR ANY DELAY IN MAKING SUCH PAYMENT.

    The Offer is not being made to (nor will tenders be accepted from or on
behalf of) holders of Shares in any jurisdiction in which the making of the
Offer or the acceptance thereof would not be in compliance with the laws of such
jurisdiction. In any jurisdiction where the securities, blue sky or other laws
require the Offer to be made by a licensed broker or dealer, the Offer is being
made on behalf of the Purchaser by Goldman, Sachs & Co., the Dealer Manager for
the Offer, or one or more registered brokers or dealers that are licensed under
the laws of such jurisdiction.

                                       3

                        INSTRUCTIONS WITH RESPECT TO THE
                           OFFER TO PURCHASE FOR CASH
                     ALL OUTSTANDING SHARES OF COMMON STOCK
           (INCLUDING THE ASSOCIATED PREFERRED STOCK PURCHASE RIGHTS)
                       OF NATIONAL COMPUTER SYSTEMS, INC.

    The undersigned acknowledge(s) receipt of your letter, the Offer to Purchase
of National Computer Systems, Inc., dated August 7, 2000 (the "Offer to
Purchase"), and the related Letter of Transmittal relating to shares of common
stock, par value $0.03 per share (the "Common Stock") including the associated
preferred stock purchase rights (the "Rights", and together with the Common
Stock, the "Shares"), of National Computer Systems, Inc., a Minnesota
corporation.

    This will instruct you to tender the number of Shares indicated below held
by you for the account of the undersigned, on the terms and subject to the
conditions set forth in the Offer to Purchase and related Letter of Transmittal.

- ------------------------------------
NUMBER OF SHARES TO BE TENDERED(1):
______________ SHARES
- ------------------------------------

                                          SIGN HERE

                                          ______________________________________
                                          SIGNATURE(S)

                                          ______________________________________

                                          ______________________________________
                                          PLEASE TYPE OR PRINT NAME(S)

                                          ______________________________________

                                          ______________________________________
                                          PLEASE TYPE OR PRINT ADDRESS(ES)

                                          ______________________________________
                                          AREA CODE AND TELEPHONE NUMBER

                                          ______________________________________
                                          TAXPAYER IDENTIFICATION OR SOCIAL
                                          SECURITY NO.

                                          DATED: ______________________, 2000
- ------------------------

(1) Unless otherwise indicated, it will be assumed that all your Shares are to
    be tendered.

                                       4