Examples of the bar method, mostly for secondary level here. Makes use of the excellent Thinking Blocks Modelling Tool. (I’m not keen on the individual tools or the individual Apps since they only focus on a single problem-type. Some of the materials have been adapted from CPD course run by the NCETM. File below contains further links to problems and other resources.
Here are some Additional Resources (forgot where they came from – apologies) that look at solving equations with the bar method.