Let me just stop you right there. You are asking the WRONG question.
Unless you are teaching an advanced Math or Science Course to a high school student who needs it to attend a university that requires it for a very specific field of study then it's the wrong question.
What Curriculum Do You Recommend to Teach... (pick anything) World War I?
Where do you recommend I begin to learn about World War I with my child?
This method of teaching you are using is based on a Greek Method. It requires the knowledge of the teacher and the curriculum as a central tool in the teaching process. It's what schools do. Don't try to emulate what the school does. We abandoned that broken institution remember?
Instead think of whatever the subject is as you would ANYTHING else in the whole wide world. If someone gave you, oh I don't know, say a freezer full of grouper. What would you do? Seriously what is the first thing you would do?
I hope you like fish, cause if you didn't know grouper is a fish.
If you generally lean on the input of others then you probably would ask on your Facebook page or in some FB group - "I got a whole bunch of grouper, what's the best way to cook it?"
Your friends will give you information (which you can find on your own by using a simple search). We like personal recommendations better and narrowing it down might help eliminate the recipe fails so, whatever. You can ask. You'll still end up in the same place.
But essentially people you ask or a simple search will give you grouper recipes. You can read up about grouper, see photos of grouper, learn where grouper is caught, how it's caught, anything and everything you ever wanted to know about grouper, including preparing it.
You would do all this from the convenience of your smart phone while the kids are in karate at the YMCA. You'd go home and you would test drive some grouper recipes. After a few times more than likely you would be a grouper master. Please note it cost nothing in this scenario to master this, nada. zip. No textbook required.
THIS is how you learn. THIS is how you should teach.
So if a child expresses an interest in World War I (or you think this is something they need to know) you respond with, "Wow I only know some basics facts about it, that's going to be really fun to learn about with you!" Then, you can ask online - you know you want to - but people will just give you curriculum choices. Or you can take up your smart phone and search "learn about World War I". You'll get more answers than you can shake a stick at.
Here are the first two that come up in my search results:
Smithsonian Magazine and History.com good start.
I love videos to begin a subject. Here is one from Crash Course "How World War I Started"
If you have older kids, these videos as starting points are perfect. This is not meant to be the sum total of the subject matter. It's meant to be a starting point.
Whenever you are studying wars it's good to consult the map. Countries rise and fall throughout history so it's great to look and see what country stands in the place where another once stood. It's also good to plug this information into a timeline to frame it in history - what came before and what came after chronologically. This is why we create a History Binder. The student takes notes and adds them to the binder based on when the events occurred. This is what I call a Reverse Curriculum.
Rather than buy a curriculum, you create one as you learn.
Also, when studying wars or history it's good to look at weapons, medicine, the rest of the world, technology, religion and in modern history pop culture and references that have endured. You'll see references to ALL these subjects in the articles and videos as you begin. You just have to follow up.
You can continue learning about this subject from other videos. Your visual and audio learners will thank you. I also love getting books from the library. Especially photo compilations, or coffee table books. I'm a big fan of biographies. Your child doesn't necessarily have to read them, but you can and then you can discuss it with them. Or you can listen to them as audiobooks. Browse the bookstores they are filled with these books and they are often on the discount tables. Pick them up you'll love having them around.
Watch good documentaries and pay attention to the questions your child asks along the way. What piques their interest? Those are the rabbit trails you want to follow with them. Write down what they asked about in a bullet journal on a post it note. Or have them write it down if they are older.
It's not important that the child memorize exact dates and names in history. It's much more important that they know the year and can frame an event in the context of other historical events. More so it's important that they can explore, discuss, and contemplate the decisions leading up to an event like a war. Understanding the course the conflict took and decisions that fueled it as well as how it was resolved is key. Above all else they should be able to see it as lessons learned. What did we learn or what did we fail to learn? In the case of WWI there is much to learn about isolationism, allies and economics as it relates to fueling conflict. You know what happens when we fail to learn from history right?
Your child might be fascinated by life in the trenches or what it was like to have planes engaging in Dogfights for the first time in history. Whatever engages them run with it. It's important they learn a subject from the perspective that most speaks to them.
It's a shame I can't recommend curriculum very often. I'd make bank on ads. But I can't, it's not best. It's not necessary. Whatever the subject approach it the way YOU would learn about it. You wouldn't go buy a textbook. You might buy a (Fill in the Blank) for Dummies type book but let's be real. Would you read that entire book? Even if you did would you retain more than the basics at best for a short while? Long term, 10 years, you will remember the highlights - window in time, key players, outcome.
Your child on the other hand, in 10 years will be able to tell you in great detail about disease in the trenches, how they handled the bodies, using the bathroom, how long they stayed hunkered down or everything you might ever want to know about the first fighter planes. Much more impressive if you ask me.
One push back I receive often is about having multiple kids and of varying ages. This works just the same. In fact, in a larger family tackling a subject like this is very exciting. The kids approach it from all different angles. They can run down their own trails and come back and report. They can team up and pair off.
You'll still need to be involved. You'll need to bounce or nurse a baby while they explain what they discovered. You might have to watch a video they found while you chop vegetables for dinner. You don't get to issue an assignment and walk away in this lifestyle, sorry.
When people say they need something structured, or something the child can do without them at all, it sounds a lot like what they want is school.
This lifestyle, this Relaxed Approach does require you to be engaged and excited about learning with your child. You are touchstone. Like "home" in a game of tag. They run off and come back and touch home. After a few years however they touch home less and less. They need less sparking along the way. The investment of time pays off in the long run because you impart to them a love for lifelong learning. You show them they don't need to have the answers, they need to know how to find the answers. They learn to research, to discern resources and to demonstrate through written and oral presentation what they have mastered.
Man oh man I wish you'd experience this. It's pretty cool to see what your kids can learn and how excited they are about learning. It's pretty cool to continue learning as an adult too. It's just cool all the way around.