I love free homeschool materials! I thought I posted this link a while ago but apparently I did not. This link will take you get free Science textbooks along with the workbooks. This will save you from having to buy the textbooks! Print what you need on the activities and you’re set! Hope this helps you on your homeschool journey.
Mcgraw Hill Science textbooks (Grades 1-6)
Reading and Writing in Science (Grades 1-6)
Activity lab books (Grades 1-6)