This is foamcore.
I found large sheets of foamcore at Wal-mart for under $5, I sliced some 2″ strips, out of which I cut rectangles of varying sizes. All/No doesn’t need a big rectangle, but P/non-P does.
I also found magnet strips in the craft section. They are backed with tape, and can be cut to make the teacher pieces.
All S is P.
Okay. I’ll show you how I do the Contrapositive.
Do the Obverse: “pull down” the All to No…
…and the P to non-P.
This results.
Slapping these cards on the metallic whiteboard is very satisfying.
Now we switch S and non-P by Converse, and get this.
By Obverse again we get the final result.
Letters from Heart's Content 
Love it! Great for hands on kids!
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Very cool! Simple and memorable!
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Thank you Ruth. This is exactly what I was looking for.
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It helped me and my students. It takes an abstract concept and makes it concrete. Glad you can use it!
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What’s on the back of “is”?
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Good question! On the back of “is” you write “is not”.
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