What happens if a contract is divisible and a party performs one of the units of the contract?

How do courts treat checks tendered as payment in full? How does a novation compare to a delegation? How does a subsequent law or regulation affect performance of the contract? How does the death of a party affect performance of the contract? How is performance affected when the subject matter of the contract is damaged or destroyed? How may a party eliminate express conditions? Under common law, is late performance a material breach? Under common law, when is counter-performance excused? Under common law, when may a breaching party recover in a divisible contract? Under contract law, what is a modification? What are conditions precedent? What are conditions subsequent? What are express conditions? What are the consequences of impossibility or impracticability under the UCC? What is an accord and satisfaction? What is a novation? What is excuse due to anticipatory repudiation? What is excuse due to improper performance? What is excuse due to insecurity about other party's performance? What is excuse due to other party's non-performance? What is frustration of purpose? What is impracticability? What is required to retract an anticipatory repudiation? What is rescission? What is the doctrine of impossibility? What level of compliance is required to satisfy an express condition? What options does the non-breaching party have in response to an anticipatory repudiation? When is a contract divisible?