I've included a document with questions for you to answer in relation to your project.
I have linked to lots and lots of websites below. The first few are from the usual child-friendly websites.
The English Heritage ones are direct links to relevant pages. This saves you clicking through links and working out what is useful and what isn't. Most of these are interactive which means you click on them to reveal videos, other images and snippets of information. However, some can be quite wordy in places, so you may need to ask for help. Don't be put off by the amount of links, you can do this over many days and explore them in your own time.
Whilst English Heritage is really thorough, you can of course look up pictures of Stonehenge on image websites such as Getty, Flickr and Shutterstock.
There is a Pinterest link to some creative things to do related to Stonehenge. Art and food related - can you tell it was me who put the pins together?
There are lots of YouTube videos as well, just be careful when searching (think about the search terms) and watching on there and ask permission first!