Tabitha is getting ready for a family trip by getting her clothes and toys together. she suddenly gets concerned and tells her mother that she will need a bigger bag. the fact that she can think this through without actually trying to pack the bag shows she is capable of using:

Spacial Reasoning, which is the ability to think objects in three dimensions and thus, to assess the capacity of specific spaces to contain a determined volume of objects. This property of human cognition was first studied in the 1980s and such studies have also played a role in the development of computer systems design, which highlights its general importance.    

ANSWER: Spatial Reasoning

EXPLANATION: Tabitha is capable of using Spatial Reasoning which is a reasoning skill in which a person is able to judge any object in three dimension and can also draw conclusion based on their limited observation over the product. Tabitha saw her clothes and toys and could use her skill to analyze and judge that all her items will not fit in that bag and she will need a bigger bag.