How to resize font in align* environment

Question

A similar question has been posted here about the align environment. However, the solution does not seem to work for align*.

Preceding paragraph.
{\small
    \begin{align*}
        a &< b
    \end{align*}
}%
Following paragraph.

Answer 1

As we have no minimal example, an example when it works. (If you have some special combination of packages, please show the minimal example, when it doesn't work for you.)

\documentclass{article}

\usepackage{amsmath}


\begin{document}


Preceding paragraph.
{\small
    \begin{align}
        a &< b
    \end{align}
}
Following paragraph.


Preceding paragraph.
{\small
    \begin{align*}
        a &< b
    \end{align*}
}
Following paragraph.

\end{document}

(When we replace \small by, say, \tiny, the result is awful, but the same sizes are easy visible.)

Answer 2

Sorry, but this never works. Consider this example, where \scriptsize is used to make the effect more apparent:

\documentclass{article}
\usepackage{amsmath}

\usepackage{lipsum} % for context

\begin{document}

\lipsum[1][1-4]

\lipsum[1][1-4]
{\scriptsize\begin{align*}
a&<b \\
c&<d
\end{align*}}
\lipsum[2][1-4]

\end{document}

With \small instead of \scriptsize the bad typesetting is still present, albeit less evident:

Here's a way to make it work without bad effects. Again, \scriptsize is used to better illustrate that the result is as wanted.

\documentclass{article}
\usepackage{amsmath}

\usepackage{lipsum} % for context

\newenvironment{sizeddisplay}[1]
 {\par\nopagebreak#1\noindent\ignorespaces}
 {\nopagebreak\ignorespacesafterend}

\begin{document}

\lipsum[1][1-4]

\lipsum[1][1-4]
\begin{sizeddisplay}{\scriptsize}
\begin{align*}
a&<b \\
c&<d
\end{align*}
\end{sizeddisplay}
\lipsum[2][1-4]

\end{document}