I am of two minds on this. 1). I had my dd double up in math for 1 semester. She did the end of Foerester's Algebra 1 and started Geometry that same semester. 2). I have heard that a few chapters could either be skipped or condensed as Foerester's Algebra 1 covers a lot of material, some of which is closer to Algebra 2 material. (But I do not remember which chapters specifically.)

I intend to have my son (14) continue with Foerster's Algebra 1 over a year and a half and again double-up with Geometry for one semester.

Michele