Tasks based on story of giants provides very good learning opportunities for developing concepts of similarity and ratios (in linear, 2D and 3D measures). This is well documented in early studies in Realistic Mathematics Education. There are interesting learning activities designed for primary students' development of these concepts, building on their intuitive understanding. Here are two relevant papers (should be available via HKU library online).

- Freudenthal, H., Janssen, G. M., Sweers, W. J., van Barneveld, G. B., Bosman, J. N., van den Brink, F. J., ... & Wijdeveld, E. J. (1976). Five Years IOWO.
*Educational Studies in Mathematics*, 185-367. [p.307, 2.6 Gulliver] - Streefland, L. (1984). Search for the roots of ratio: Some thoughts on the long term learning process (Towards... a theory).
*Educational Studies in Mathematics*,*15*(4), 327-348.