40 x 75 cat # is BPEZ040X075
50 x 75 cat # is BPEZ050X075
Do a search for 'zip-lock' & it'll show all the sizes...the biggest is 360mmx x400mm!
Ditto what Lada said too, we get the kids to set up 3 bags: glucose, starch, starch+amylase all in beakers of water....then test for sugar & starch with the benedict's & iodine straight away, & 24 hours later (I always spike the beakers with a little glucose too of course
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A cute little visual demo to do while they're getting their bags & beakers set up is to fill a bag with some starch solution & pop it in a beaker of diluted iodine. Within 10-15 mins the starch in the bag's turning blue-black, but the iodine in the beaker stays the same.