Number, Measurement and Space, module establishes equivalence of sets by a one-to-one exchange of objects. Eg Upsetting equivalance (destroying conservation of numbers) by adding one object to a set, or taking one away, helps introduce vocabulary for comparing quantity
Specific Gravity Metal Cylinder Set Copper, Zinc, Aluminium And Steel, Four Different Metal Cylinders Each Measuring 38 mm Long X 10 mm In Diameter, Made Of Aluminium, Zinc, Copper And Steel.