Dear Wolfgang, According to your advice, I am able to make a working example as following. \usemodule[animation] \setupinteraction[state=start] \startuseMPgraphic{Circles}{s} numeric sn, L, N; path p, q; p := fullcircle scaled 72; L:=length p; N:=20; sn := \MPvar{s}; q := subpath (0, sn/N*L) of p;% draw q withcolor red; fill fullcircle scaled 3 shifted point length q of q withcolor blue; setbounds currentpicture to unitsquare shifted (-0.5,-0.5) scaled 75; \stopuseMPgraphic \starttext \startanimation[menu=yes, menucolor=blue, framerate=5] \dorecurse{20} {\expanded{\frame{ \useMPgraphic{Circles}{s=\recurselevel}}}} \stopanimation \stoptext One more question. In metafun document, there is a command \setupMPvariables before \startuseMPgraphic. But we don’t use it in this example. Hence I think that it is not necessary always. Is there any case in which we have set the MPvariables? Thank you. Best regards, Dalyoung