With two kids needing a calculator, the teacher recommendation was for the TI-84 and it's hefty price tag. But when searching on-line, I've discovered the Numworks calculator. Not only is it 100$ cheaper that the TI, it works much quicker, and is programmable in my preferred language: Python. Also all project is open sourced i.e. my son printed a 3d case in his preferred color. All the source code, schematics and BOM is online, so in case something breaks, you can fixed yourself. It's now the teacher recommendation for all his classes.