I am not sure what subject area you want to focus on, which would make a difference for living book suggestions. You could put together a mix of resources for family with additional work for your 8th grader, like extra reading, experiments and narrations. What are your science plans for high school? You want to make sure your 8th grader will be prepared for that.
Our family liked the Physics 101 DVD set this year for grades 6 & 9. I am not sure about your first grader with it though. They also have Biology 101 & Chemistry 101 we plan to use in the future.
Other dvd sets we liked as a family are Your Backyard Birds and their new one on the Monarch Butterfly. They are each an hour long plus bonus material. High quality for an independent film. Highly recommend.
For other nature, we always liked BBC Blue Planet and Planet Earth DVD sets. But there are occasional comments about the age of the earth. Excellent video footage. For creation -based check on Nature of God sets on Hawaii/Ocean Adventures and Great Lakes / Wilderness Discoveries. Creation Proclaims has 4 dvds about animals, recommended for ages 8+.
My son has enjoyed reading through the Wonders of Creation series from Master Books the past few years. They offer various topics. He did written narrations with these.
So you could schedule a day a week for each:
1. Video
2. Nature Study with journal/sketch book or museum/nature center field trips and local/state/national parks for visitors center, hikes, programs. Seasonally you could garden, pick berries, fruit, pumpkins, etc. in your area.
3. Experiment
4. Reading (living books, picture books, biographies, nature lore) as a family or independent reading
5. Extra for 8th grader