UCC § 2-206
Offer and Acceptance in Formation of Contract
(1) Unless otherwise unambiguously indicated by the language or circumstances (a) an offer to make a contract shall be construed as inviting acceptance in any manner and by any medium reasonable in the circumstances; (b) an order or other offer to buy goods for prompt or current shipment shall be construed as inviting acceptance either by a prompt promise to ship or by the prompt or current shipment of conforming or non-conforming goods, but such a shipment of non-conforming goods does not constitute an acceptance if the seller seasonably notifies the buyer that the shipment is offered only as an accommodation to the buyer. (2) Where the beginning of a requested performance is a reasonable mode of acceptance an offeror who is not notified of acceptance within a reasonable time may treat the offer as having lapsed before acceptance.
Professor's notes
Elements: (1) unless otherwise unambiguously indicated, (a) an offer to make a contract is construed as inviting acceptance in any manner and by any medium reasonable in the circumstances; (b) an order for prompt shipment invites acceptance by either a prompt promise to ship OR prompt shipment of conforming or non-conforming goods (non-conforming shipment is acceptance plus breach unless seller seasonably notifies it is offered only as an accommodation); (2) where the beginning of performance is a reasonable mode of acceptance, an offeror not notified within a reasonable time may treat the offer as having lapsed.
Common misunderstanding: students miss the non-conforming shipment trap in (1)(b). Ship non-conforming goods without an accommodation disclaimer and the seller has BOTH formed a contract AND breached it on the same act. This rejects the common-law "unilateral acceptance equals matching performance" rule and protects buyers from sellers who would ship junk and disclaim.
Text
UCC § 2-206. Offer and Acceptance in Formation of Contract.
(1) Unless otherwise unambiguously indicated by the language or circumstances
(a) an offer to make a contract shall be construed as inviting acceptance in any manner and by any medium reasonable in the circumstances;
(b) an order or other offer to buy goods for prompt or current shipment shall be construed as inviting acceptance either by a prompt promise to ship or by the prompt or current shipment of conforming or non-conforming goods, but such a shipment of non-conforming goods does not constitute an acceptance if the seller seasonably notifies the buyer that the shipment is offered only as an accommodation to the buyer.
(2) Where the beginning of a requested performance is a reasonable mode of acceptance an offeror who is not notified of acceptance within a reasonable time may treat the offer as having lapsed before acceptance.
Source: UCC Article 2 (post-2022 amendments), as in the LawJ statutory corpus.