Hier ein Beispiel
\documentclass[12pt, a4paper,xcolor=dvipsnames]{beamer} \usetheme{Dresden} \usecolortheme[named=red]{structure} \usepackage{xcolor} \usepackage[ngerman]{babel} \usepackage[utf8x]{inputenc} \usepackage{amsmath,amsfonts,amssymb} \usefonttheme[onlymath]{serif} \newcommand{\p}{\partial } \begin{document} \begin{frame}{} Test Test Test Test Test \begin{align*} \onslide<2->{ \only<1-6>{ \frac{\p r^2}{\p x}= \onslide<3->{2r\frac{\p r}{\p x}=} \onslide<4->{ 2x \Leftrightarrow } \fcolorbox{white}{white}{$\onslide<5-> {\dfrac{\p r}{\p x}=\dfrac{x}{r}} \onslide<6->{=\cos\varphi.}$} } \only<7->{ \frac{\p r^2}{\p x}= 2r\frac{\p r}{\p x}= 2x \Leftrightarrow {\fcolorbox{red!70!black}{red!30!white}{$\alert<11>{\dfrac{\p r}{\p x}}=\dfrac{x}{r}=\cos\varphi.$} } } } \end{align*} \onslide<8->{Hier verschiebt sich etwas. } \onslide<9->{ \begin{align*} \only<8-12>{\frac{\p y}{\p x}= \onslide<10->{0= \alert<11>{\frac{\p r}{\p x}} \sin\varphi + r\frac{\p \varphi}{\p x}\cos\varphi \onslide<12-> { \Leftrightarrow \fcolorbox{white}{white}{$\dfrac{\p \varphi}{\p x}=-\dfrac{r}{\sin\varphi}.$} }}} \only<13->{\frac{\p y}{\p x}= 0=\frac{\p r}{\p x} \sin\varphi + r\frac{\p \varphi}{\p x}\cos\varphi \Leftrightarrow \fcolorbox{red!70!black}{red!30!white}{$\dfrac{\p \varphi}{\p x}=-\dfrac{r}{\sin\varphi}.$} } \end{align*} } \onslide<14->{ Das ist ein Test } \onslide<15->{ \begin{align*} \fcolorbox{red!70!black}{red!30!white}{$\dfrac{\p r}{\p y}=\sin\varphi$} \quad \fcolorbox{red!70!black}{red!30!white}{$\dfrac{\p \varphi}{\p y}=\dfrac{\cos\varphi}{r}.$} \end{align*} } \end{frame} \end{document}
Beste Grüße
Freddy