We did the oceans challenge a couple of years ago with guides. It fitted in with an aquarium sleepover and a fishing themes farm to fork Tesco trip. We quite liked it a lot although we tweaked bits to suit us. The current experiments were good fun. (I can't remember if this was a tweaked bit) we raised up a large Pyrex dish and put mugs of hot water underneath to hear spots up and added drops of food colouring to look at currents forming. We also had some ice cubes to add to the dish to see how it changed. Baby science but it was good to take it further and play with it. Lovely badge too!
We did the Sustainable Dev with our Guides this term. TBH it was a bit dry. They enjoyed some of the activities - there is one about making jeans that made an impression - but I thought there was a lot of overlap in the acitivities, and there wasn't enough extra information for leaders to help in the discussions.