  Quiescent galaxies having more compact morphologies than star-forming
galaxies has been a consistent result in the field of galaxy evolution. What is
not clear is at what point this divergence happens, i.e. when do quiescent
galaxies become compact, and how big of a role does the progenitor effect play
in this result? Here we aim to model the morphological and star-formation
histories of high redshift (0.8 $<$ z $<$ 1.65) massive galaxies
(log(M/M$\odot$) $>$ 10.2) with stellar population fits using HST/WFC3 G102 and
G141 grism spectra plus photometry from the CLEAR (CANDELS Lyman-alpha Emission
at Reionization) survey, constraining the star-formation histories for a sample
of $\sim$ 400 massive galaxies using flexible star-formation histories. We
develop a novel approach to classifying galaxies by their formation activity in
a way that highlights the green valley population, by modeling the specific
star-formation rate distributions as a function of redshift and deriving the
probability that a galaxy is quiescent (PQ). Using PQ and our flexible
star-formation histories we outline the evolutionary paths of our galaxies in
relation to stellar mass, Sersic index, $R_{eff}$, and stellar mass surface
density. We find that galaxies show no appreciable stellar mass growth after
entering the green valley (a net decrease of 4$\%$) while their stellar mass
surface densities increase by $\sim$ 0.25 dex. Therefore galaxies are becoming
compact during the green valley and this is due to increases in Sersic index
and decreases in $R_{eff}$.
