Final answer:
The recipe requires 19.5 teaspoons of vanilla extract.
Step-by-step explanation:
To convert tablespoons to teaspoons, you need to know that there are 3 teaspoons in 1 tablespoon. Therefore, to find out how many teaspoons of vanilla extract the recipe requires, you can multiply the number of tablespoons by 3. In this case, 6.5 tablespoons multiplied by 3 equals 19.5 teaspoons. So, the recipe requires 19.5 teaspoons of vanilla extract.