Dependent Variable $($Y$)$: Test$-$Scores Model $1$ Model $2$

Y$-$intercept $161\mathrm{.}45-100\mathrm{.}785$

$(3\mathrm{.}974)(1\mathrm{.}219)$

Class Size $-3\mathrm{.}78-2\mathrm{.}57$

$(0\mathrm{.}180)(0\mathrm{.}230)$

Socio$-$Economic Status $12\mathrm{.}571$

$(2\mathrm{.}312)$

Quality of Instruction $52\mathrm{.}319$

$(0\mathrm{.}22)$

R$-$squared $0\mathrm{.}3080\mathrm{.}988$

Compare the R$2$ of $0\mathrm{.}308$ and $\mathrm{.}988.$ Which is the more powerful model for explaining variations in student academic outcomes $($Y$)?$ Why?