It is so important to get your daughter engaged in her own learning as soon as you can. In terms of math specifically... the sooner kids "check out" the more gaps they tend to develop which impacts their learning all the way up. Here is what I recommend...
I believe that intrinsic motivation is most desirable so... if you can find something your daughter is truly interested in and build off of this, that would be optimal. For example, what are her interests outside of school? Think hard and pick something she is truly passionate about. Then ask yourself how you can connect this to the math she is learning? Next, try to create an intriguing little project to do at home based on this topic to jump start her participation in learning. (If she is in grade four, she is likely learning about place value for large numbers up to 10,000 as well as learning how numbers compose or decompose for values up to 10,000. However... she may not truly understand how big ten thousand is... try and give her context through the activity you create). Make the project short, interesting, and fun (and again... be sure it connects to something she cares about). I suggest that you do it with her -or at least do some of it with her. When she is done the project, have her share it with you (this is critical!). When she does, ask questions so she can showcase her learning and be sure to comment on her
effort (Effort is key to creating motivated learners! It is important you do not say she is 'smart', instead say she worked hard and you are so proud of her for her effort). Then try to extend this experience by and seeing if she would like to turn this little project into something else like a second project or perhaps make a blog or video about it. (I saw a fantastic video blog done by a five year old... kids love this as they can be the start of their own show!) If you don't want her to publish it... she does not have to. An option would be to create a file on a computer or, in a cabinet, where she can keep it. Additionally, if she had the opportunity to teach it to someone, that is ideal! Finally, if her teacher is open to it, have your daughter share this with him/her in some way. Making learning public however you can is important for developing your daughter's sense of pride towards her own learning.
So... my advice again is to start getting your daughter interested and excited about learning math by doing the above project in an attempt to develop intrinsic motivation. Do this more than once if necessary. Then try and connect this to the math she does at school. Personally, I do not recommend extrinsic motivation as using extrinsic rewards can jump start some kids, but research shows that it usually leads to the previous, undesired behaviour reoccurring sooner or later.
In sum, the key to fostering intrinsic motivation are: (a) praising effort not intelligence (b) giving students ownership of their learning, (c) making the learning public, and (d) connecting what students are learning to something they intrinsically care about. (This is especially true for math which many kids think is not conected to anything in the real world).
If you want to read more about motivation and learning, I highly recommend the book Mindset by Carol Dweck, and the book Drive by Daniel Pink.
