WhatsApp has designed their conversations to have end recipients in control of the conversation. This article describes how you can have a free flowing conversation with a student in your funnel.
A WhatsApp session lasts for 24 hours after the last inbound message you receive from a user.
Outside of a WhatsApp24 hour session, you may only send a message following a pre-approved template to the user. Any message that doesn't match a pre-approved template is considered a free-form message.