Working systematically- nRich
Website

Finding All Possibilities Upper Primary

These activities focus on finding all possible solutions so working in a systematic way will ensure none are left out.
Year 3 and 4 problem solving-TES
Resource Excellent problem solving pack with problems for Years 3 and 4. There are a number of correspondence problems in this pack.
Correspondence-Primary Resources
Website A number of correspondence problems on the Primary Resources site: See Clothing Combinations, T Shirt combinations, Houses and Flowers,  
Correspondence- how many outfits?
PowerPoint I have 4 shirts one is red, one yellow, one white, and one blue. I have 2 pairs of pants that are black and khaki and one skirt that is dark blue. I can wear all these with all 4 shirts. How many different outfits do I have?
Study Ladder
Website Lots of resources from this Australian site- but you must join.
Third Space Learning
Website  Mainly aimed at Years 5 and 6 , with useful resources, but also a website to keep an eye on as they will undoubtedly expand more .
Mathematics Mastery
Website Some examples ( full flip charts  and lessons ) of a Mastery approach.