Severin Hacker - 27 Jul 2021 Form 3 Insider Report for Duolingo, Inc. (DUOL)

Footnote F1

Each share of Class B Common Stock is convertible at any time at the option of the Reporting Person into one share of Class A Common Stock and has no expiration date. Each share of Class B Common Stock will convert automatically into one share of Class A Common Stock in connection with: (i) any transfer, whether or not for value, except for certain permitted transfers further described in the Issuer's amended and restated certificate of incorporation, (ii) such time as the aggregate number of shares of Class B Common Stock outstanding ceases to represent 5% of the aggregate number of shares of Common Stock outstanding, and (iii) the death of the Reporting Person.

Footnote F2

Shares held by SBH Trust dated March 10, 2020, of which Reporting Person is Trustee.

Footnote F3

1/48th of the shares subject to the option vest on each monthly anniversary measured from January 1, 2019 (the "Vesting Commencement Date"), such that 100% of the shares subject to the option will be fully vested and exercisable on the fourth anniversary of the Vesting Commencement Date.

Footnote F4

1/48th of the shares subject to the option vest on each monthly anniversary measured from January 1, 2020 (the "Vesting Commencement Date"), such that 100% of the shares subject to the option will be fully vested and exercisable on the fourth anniversary of the Vesting Commencement Date.

Footnote F5

1/48th of the shares subject to the option vest on each monthly anniversary measured from January 1, 2021 (the "Vesting Commencement Date"), such that 100% of the shares subject to the option will be fully vested and exercisable on the fourth anniversary of the Vesting Commencement Date.

Footnote F6

Each Performance-Based Restricted Stock Unit ("PSU") represents a contingent right to receive one share of the Issuer's Class B Common Stock upon vesting. The PSUs vest upon the satisfaction of both a service-based condition and a performance-based condition. The service-based condition is satisfied as to 25% of the PSUs on each anniversary of the completion of the Issuer's initial public offering of Class A common stock based on the Reporting Person's continuous service as CTO to the Issuer through the applicable vesting dates, subject to acceleration upon a cessation of service as CTO as a result of death or permanent disability.

Footnote F7

(continued) The performance-based condition will be satisfied upon the Issuer's Class A common stock achieving certain stock price hurdles over a period of ten years. Vested PSUs will be settled by the issuance of the underlying Class B Common Stock on the first anniversary of vesting, subject to acceleration upon a termination of employment or a change in control of the Issuer.