Everyone tends to "Google" images. To avoid copyright breaches, follow this process:
1) Search in Google images
2) Click on Tools
3) Click on Usage Rights
4) Select Labeled for reuse - these images are usually from the Public Domain or Creative Commons.
See below for other specialized, publicly available sources with more refined search options.
Other Public Domain Image Sources
Remember since you are working in an academic environment referencing will ALWAYS be required. Referencing means you are covered in relation to copyright and plagiarism by acknowledging the resource is not yours and it also helps you or someone else find it again if required. For more information on copyright and referencing have a look at the above tab called APA Referencing
Note : All Ara computers can access Audacity which is software you can use to record your own sounds.