In Act 1 of The Crucible, why does Abigail tell John Proctor the truth about the other girls being in the woods?
Despite the break-up of their relationship, Abby and John still have feelings for each other. This means that they can express themselves frankly to each other in a way that simply wouldn't be possible with anyone else. However, there are limits. Abby may feel completely at ease about expressing her innermost desires to John, but when it comes to what happened in the forest that night, she can't quite bring herself to tell the full story.
Abby's attempt to downplay the significance of the weird pagan dancing shows how devious and manipulative she really is. She doesn't just want to manipulate John's emotions; she also wants to manipulate the truth, to distort history to suit her own needs. Her reluctance to spill the beans comes in useful later on, as Abby sets about making false accusations of witchcraft against innocent people. Had it been widely known what she was really up to in the forest, then she wouldn't have been able to do that.
Abigail likes to stir up trouble. Obviously this scene reveals that they actually had an inappropriate relationship together in the past. These types of relationships elicit a certain amount of trust, even beyond the actually term of the relationship. However, when Abigail says,
"We were dancing in the woods last night, and my uncle leapt in on us. She took fright is all,"
she is trying to downplay what actually occured in the woods. The girls were actually trying to conjure up spirits. Abigail tries to make it seem like it was just a little bit of fun, but the entire truth doesn't come out between Abigail and Proctor at that moment. In fact, she changes the subject back to their relationship.
Later in the act more pieces of truth come out from other girls and are revealed to the reading audience. The townspeople do not have all of the information we do.