✏️ Ratio & Proportion Workbooks from Kumon. For kids who would benefit from some extra practice, the Kumon math workbooks are an appealing and cost-effective supplemental resource. Kumon’s Focus on Speed, Proportion & Ratio workbook is geared to kids aged 10 and up. – Elementary

✏️ Prealgebra modules from Khan Academy. Khan Academy offers a wealth of free math educational resources, including a large library of instructional videos and online practice problem sets. The Ratios, Rates, and Proportions module covers ratios, rates, percents, and proportions.

✏️ Arithmetic modules from CK12. CK12 offers free, adaptive online practice across all areas of math. In Percents, practice working with percent. In Conversions, try converting between percents, decimals, and fractions. In Measurement, work with scale factors. The Fractions module has a section on ratios. – Elementary

📖 Cut Down to Size at High Noon by Scott Sundby. Here’s a good literature link for teaching proportion and scale drawing. "The town of Cowlick turns out for a scale-drawing showdown when a tough-talkin' stranger challenges the local hero." – Elementary

​📖 If You Hopped Like a Frog by David Schwartz. Here's a good introduction to ratio and proportion, with a fun premise: "Did you know that a frog can jump 20 times its body length? Or that an ant can lift an object 50 times its own weight? By applying these ratios and proportions to their own bodies, readers will discover what they could do if they had the amazing abilities of animals." – Elementary