A puzzle to close out Adult Education Family Literacy (& Numeracy) Week!

Here is a numeracy puzzle for us to wrap up AEFL(&N) week!

Can you put the numbers 1 to 8 in each of the squares so that each side adds up to the middle number?  



So I said to myself "okay, the side with fewest spots gets the biggest two:  5 and 7."  

Then I played "over under" thinknig and " hmmm... this is too big, let me shift down."   It took less than 3 minutes on the first one!   

I'm not counting on it being possible to do them all since thse kinds of puzzles work like that... 

for thirteen I thought "oh, there are *two* 'short' sides.   They'll want the middle sizedoptions so let's plug in 7 and 6  and 8 and 5 ... but no combinations work with that... so I resolved to "okay, pairs 1 12, 2 11, 2 10 don't work so let's try 4 and 9 with the 5 and8."  Then combos on the two vertical sides... if one didn't work I'd flip the two and try that... so 

SO I went to logic and the only way to get to 13 is using up the bigger numbers, and ... they're just not big enough to add up to 13 wtihout repeating, and that would be the same for anything bigger, too.   So!  Repeating would have to happen.