FRQ 3 Array and ArrayList

The third free response question has students analyzing and manipulating data stored in array or ArrayList objects or sometimes using both types of data structures. This question has a part A and a part B.

Be sure to attempt each part.

As mentioned in prior posts, be sure to always attempt each part. Sometimes, students will find that they understand the directions for part B better or find that part B is easier. Students might also find that while solving part B, the solution to part A becomes clearer.

You have to traverse the data structure.

This traversal could be a straight through traversal from beginning to end or it could do something more interesting where it is asking you to compare adjacent elements, identify a run of element, search and find an element that meets a specific criteria, etc.

Call methods for the newly introduced class.

You will likely be given a new class for the data being stored in the ArrayList. This will likely require that you access the data from the ArrayList and then call methods from this new class on that data.

For example, in the 2022 FRQ 3 the Review class is provided. Students are asked in part A to return the average of all the reviews. To do this, students need to sum up all of the ratings in the array. Once they have accessed the element in the array, they need to then call the getRating method. A common mistake students make is to access the element and try to add that to a sum. But accessing the element gives you a Review object and not a number.

Use the methods and data provided for you.

If you are provided with a new class, the data and methods provided are meant to be used in the solution. Be sure to pay attention to provided:

instance variables
constructors
methods
methods return type
methods parameters.

Know the standard algorithms.

In the CED, there are some standard algorithms listed for manipulating array or ArrayList objects. Provide your students with a lot of practice with these standard algorithms as well as modifying these standard algorithms. Here is a list of the array algorithms your students should have experience with:

determining a minimum or maximum value
computing a sum, average, or mode
determining if at least one element has a particular property
determining if all elements have a particular property
accessing all consecutive pairs of elements
determining the presence or absence of duplicate elements
determining the number of elements that meet a specific criteria
shifting or rotating values from left or right
reversing the order of elements

Here is a list of the ArrayList algorithms your students should have experience with:

inserting elements in the ArrayList
deleting elements in the ArrayList