Disco Double Checkmates!

Howdy chessers! Have you discovered any checkmates lately? Here are a few that use the important tactic discovered double check. Double check is the most powerful kind of check!  Instead of three ways out (move, block, or capture), there is only one: the king must move! By, Mrs Jessica E Prescott (aka BoundingOwl).

Each of these checkmates will be White to move and mate in two. Look for a pattern as you go...

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I'll do the first one for you. Find the pieces that are lined up with the king. The great thing about double checks is your piece is invincible!
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1.  There is someone far away pointed directly at the king. Who is in her way?  Move that piece; then bring the queen in for mate!
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2.  Do you see three pieces all lined up? Move the piece in the middle and the piece behind gives check!
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3.  Make a forcing double check before getting mated yourself! Don't let the king out. Think hard!
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4.  Here the minor pieces alone give mate!
Great work, friends! What pattern did you recognize? 
Each first move began with a knight! Now go teach your little sister to play chess. See you next time!