in Mathematica at least, you can use TraditionalForm to format your equations like maths. and what's more, you can edit things in that form without dropping out

in Mathematica at least, you can use TraditionalForm to format your equations like maths. and what's more, you can edit things in that form without dropping out of it. you can also make palettes for commonly used symbols and such. it's not a magic blackboard, but with the symbolic nature of Mathematica and the rendering, it's kinda close.