For worksheets, Singapore would be the one I'd recommend. I like the "Intensive Practice" workbook if you're only getting one. The problems are significantly more challenging. Also, remember that it's about 1 semester ahead of where American schools usually are, so 2A is really more like 2nd semester of 2nd grade, not 1st semester.

Some homeschoolers and afterschoolers like Saxon, but it has too much repetition for my taste for a GT kid. Still, it's the other biggie for worksheets.

Aleks and EPGY are online sources, but I think you can print things out, too. They are very well liked by GT families.

You can't beat Aleks and Singapore for the prices! I's say start there. Aleks has a free trial for a month, and Singapore offers free assessment tests.

Good luck, and welcome!

Kriston