I wonder if any of you have stumbled across any resources for teaching balancing sums. A large group in my class are struggling with the concept, despite doing lots of work on missing numbers and inverse operations. What they don't get is this type of this type of thing: 25 - 4 = _ x 7 but they could calculate _ x 7 = 21. What I'm really looking for is some kind of bucket scales where I can put calculations on each side and they need to balance so that kids can visualise the concept. Is there such a thing? I've searched but with no luck. Any ideas? please.