I found this while reading one of my Go books, and thought you might like it.
(;AB[bj]AB[bk]AB[ci]AB[ch]AW[bi]AW[ai]AW[bg]AB[ei]AW[cj]AW[ck]AW[cl]AW[bm]AB[cf]AW[df]AW[eg]C[Taken from 'Go Proverbs' by David Mitchell. Black to kill, and connect his two groups.]AP[goproblems]
(;B[bh];W[ah]
(;B[af];W[bf];B[aj]
(;W[ag];B[be];W[ae];B[cg]C[Ouch. White is dead and Black is connected.RIGHT])
(;W[cg];B[ag]C[White decides to cut his losses here, but Black is still nice and connected... and alive with points, of course. RIGHT]))
(;B[cg]
(;W[bf]C[VERY bad mistake by White! Punish him for it!]
(;B[be];W[ak]C[Wrong. The B10 group need not be sacrificed. There is a way for B10 and C11 to connect.])
(;B[aj];W[ag];B[be]C[RIGHT])
(;B[ag]C[RIGHT];W[af];B[aj];W[ag];B[be]C[Ouch! White is dead. RIGHT]))
(;W[bl]
(;B[bf];W[ak];B[ag];W[aj]C[Wrong! B10 doesn't have to be sacrificed for Black to live.])
(;B[ag];W[af];B[bf];W[ak];B[ag];W[aj]C[Wrong! White got way more from this than he should've.])))
(;B[ag];W[af];B[aj];W[ag];B[cg];W[bl]C[Wrong! If you got this variation, you got it because you did little-to-no reading before you starting plopping down stones.]))
(;B[cg];W[ak]C[Wrong.]))