I don't have a first grader anymore. However, my favorite thing for social studies in the early grades is to pick a country for each month. Then, go to the library and get a "true" book about the country, some folktales from that country, and possibly a video. There is a great video series "Families of the World" that our library has. Here is one example from that series:
Then, we learn about the country, find it on the map. We identify the continent, borders, and major landmarks. We read the stories, and watch the video. If I can find an art/craft project to tie in, we do it. Finally, we find a recipe to make from that country. (Exception: for China, we went out for Chinese food).
Science: I like to do hands on science. I like to follow their interests whenever I can. We have had years where we just get different experiment books and try what is interesting. We plant gardens, etc. That being said, I love the science from Pandia Press. Their level ones are perfect for early elementary. You use some books from the library, you do some fun labs, but it is laid out for you so it is easy to implement. They have a "try before you buy" option on their website. I highly recommend making use of that offer. For their level one books, I was happy with the ebook. I wish I would have bought the print book for the level 2. That might not be right for you--another reason to do the try before you buy. That try is digital, so you can see how much you might feel you need to print. With this curriculum, Life and Earth/Space are great for first grade. I think the Chemistry is keeps the audience longer, so I would do it later (3rd or 4th). Here is their link: http://www.pandiapress.com/?page_id=50