A unit study centers around a topic or theme and incorporates multiple subjects into that study. Some people say a unit study needs to include all academic subjects for it to actually be a real unit study, but I say that's impossible every time (especially with older kids) and too much pressure, so as long as it includes multiple subjects, I call it a unit study.
Here's a link explaining unit studies: https://www.thehomeschoolmom.com/homeschooling-styles/unit-studies/
I almost always center my unit studies around a literature selection.
For example, we did a literature-based unit study centered on The Scarlet Letter.
I knew I wanted to include the following subjects in this study:
- Literature, writing and vocabulary
- History
- Geography
- Art History
- Government
- Logic
I saw no way to incorporate science, so I didn't include it. I guess if you were really creative, you could study ship-building or physics of ships, etc. But, I think that would be a bit too much for me.
I brainstormed things I wanted to cover for each subject.
Literature, writing and vocab - we would read The Scarlet Letter and work through the Progeny Press literature guide, using some of the questions in the guide as writing prompts.
History - I wanted my student to learn about the Puritans, Puritan Plantation, the Native Americans that lived in the area at the time, the Mayflower, the Mayflower Compact, the colonies in New England, the Salem Witch Trials, etc.
Geography - I included map work of some kind and videos about the area.
Art History - we looked at paintings done of the Puritans and colonists in New England during the 1600s. We also viewed museum collections (online) that included paintings of ships, landscapes, Native Americans, etc, of the time period
Government - we read a book about the US justice system. We also read the original transcripts of the Salem Witch Trials. These are actually available online and they're very detailed.
Logic - we went through a book about logical fallacies and this went well with reading the trial transcripts
My next step was the estimate how long it would take us to work through The Scarlet Letter and to tailor the other subjects to the length of the book. I think we spent 8 weeks reading the book (it was a difficult book for my daughter at the time). So, I needed to come up with 8 weeks of material in each subject.
I looked for resources and more detailed plans for each subject.
Literature, writing and vocab
This was easy, because I bought a literature guide for The Scarlet Letter from Progeny Press. We didn't do everything in the guide, but I assigned 1-2 writing assignments per week and I pulled these writing assignments from questions in the literature guide. Besides the writing assignments, I went through the guide verbally with my student after chapter.
History
For this unit study, I chose videos on Youtube. I assigned documentaries about Plymouth Plantation, videos that gave a tour of the settlement (there is a modern recreation nearby the original that you can tour) and documentaries about the Native Americans who lived in the area at the time. We watched a documentary about the Salem Witch Trials and videos about other topics related to 17th century New England.
Geography
I can't remember what resources I used for this, but when I do map work, I usually print out maps and assign places to label on the map. There are printable maps everywhere online.
Art History
The best place I've found to view and read about artwork is museum websites. Many museums have portions of their collections on their websites. On some museum websites, you can do close-ups of the painting and even see brushstrokes.
Government
Logic
Like I already mentioned, we read a book about logical fallacies.
With lists of resources to teach each topic, I could break everything up into an 8 week unit study. I basically divided a piece of paper into eight sections and then listed what I wanted to cover each week.
This is just one way to put together a unit study. There are pre-made unit studies out there, as well as curricula that cover years of homeschooling in unit study style.
Some links about unit studies (which maybe explain things better than I do).