This tesuji has to be somewhere on this site, but I can't find it -- and I always forget it!
(;AP[goproblems]AB[ii]AB[ih]AB[ki]AB[kj]AB[kk]AW[ji]AW[jh]AW[kh]AW[lh]AW[kf]AB[ig]AB[gh]AB[ll]AB[gi]AW[gj]AW[fj]TR[ii]TR[ig]TR[ih]TR[gi]TR[gh]TR[ki]TR[kj]TR[kk]C[White just played the marked stone. How can black connect?](;B[ik](;W[jj](;B[hl]C[Great job!RIGHT])(;B[ij];W[jk];B[jl];W[il](;B[im];W[hl])(;B[hl];W[im])(;B[hm];W[hl]))(;B[jk];W[ij];B[hj];W[hk]))(;W[ij](;B[hj];W[jj](;B[hl]C[RIGHT])(;B[hk];W[jk];B[jl];W[il]C[In some cases, J8 may not work for white, but without contet, don't leave the connection to chance!]))(;B[jj];W[hj])))(;B[jj];W[ij](;B[ik];W[hj])(;B[hj];W[ik])(;B[hk];W[hj]))(;B[ij];W[jj](;B[jk];W[ik](;B[il];W[hk])(;B[hk];W[il])(;B[hl];W[hk]))(;B[ik];W[jk];B[jl];W[il](;B[hl];W[im])(;B[im];W[hl])(;B[hm];W[hl])))(;B[hk];W[jj](;B[jk];W[ij];B[hj];W[ik];B[il];W[hl](;B[gm];W[gl])(;B[hm];W[gl])(;B[gl];W[hm]))(;B[ik];W[jk];B[jl];W[il](;B[hm];W[im];B[in];W[jm])(;B[im]C[A ladder is not good enough.];W[hl])(;B[hl];W[im]))(;B[ij];W[jk];B[jl];W[ik](;B[il];W[hj])(;B[hj];W[il]))(;B[hj];W[jk];B[jl];W[il](;B[ik];W[im])(;B[hl];W[im])))(;B[hj];W[jj]))