Why would the disciples think that the “leaven” that Jesus said meant the “bread” that they forgot to bring?

Why would Jesus ask the disciples how many baskets of fragments of bread were left previously?

Why would Jesus blame the disciples that their hearts were still hardened (v17)?

According to Matt 16:12, the “leaven” that Jesus said meant the “doctrine” . How did “leaven” relate to “doctrine”? (I Cor 5:6-8)

What is the main difference between the doctrine of the Pharisees and that of the Sadducees? (Acts 23:8) If the disciples accepted the doctrine of the Sadducees, how risky was the situation?

How did the Sadducees treat the early church believers? (Acts 4:1-3, 5:17-18)

What is the meaning of “the leaven of Herod” (v15)? (Luke 9:7-9, 23:8) What is its threat to the faith of the disciples?

How did Herod treat the early church? (Acts 12:1-4)

According to Matt 13:33 and I Cor 5:6-8, what is the meaning of the “leaven” used? If this meaning is applied to the leaven of the Pharisees and the like, how would you interpret verse 15?

How does Jesus’ saying in verse 15 apply to today’s Christians?