Since you are using images for an educational scholarship purposes, and you will not be making any money from your assignment, most of the time you can reuse an image without requiring permission.
However, to avoid any potential issues of copyright infringement it is better to use images that are already marked for reuse. This may seem challenging, but many of the most common image search sites now have advanced search features that allow you to limit your results to images that are allowed for reuse.
After completing your Google Image Search, click on the "Seach Tools" link, then click the "Usage Rights" drop-down menu. Make sure to select a license that allows for reuse.
After completing your search in Flickr, click on the "Any License" drop-down menu. Selecting "All creative commons" will give you the widest array of results that are available for reuse.