Hi and welcome! I also have a first grade daughter who's not being challenged at all by school math. Our approach to this is still evolving, but here are some things we are doing at home. Our goal is more for her maintain her feeling that math is fun and interesting, and to have a family culture in which we view math as something fun to play with and explore (Before kids, DH and I used to solve probability problems for fun as a way to relax in the evening...so this comes natural to us!).
--Math games/problems at the dinner table or as a bedtime game (everyone gets to take turns asking another person mental arithmetic questions).
--Bedtime Math books - these have nice story problems you can do at several levels of difficulty.
--Board games - we used to do Sum Swamp, but that's now too easy. I'm ordering Prime Climb for a holiday gift and can let you know how that is.
--This is more loosely related to math, but we do lots of puzzles and spatial logic games, like Tangrams, Connect 4, Rush Hour, etc.
Both kids (DD6 and DS4) love all of the above and demand these activities daily. In addition, I've signed them up for Dreambox. It's not my daughter's favorite activity, but I do require her to use it 2-3 times a week, as it's an adaptive program and is thus able to give her some on-level, more challenging math practice. It also covers a broader range of topics than what we can do through games/play. She's OK with using it to earn some extra video time. I like it because I think it's a good program for building "deeper" math thinking skills (as opposed to math fact drill and kill).
