Instead of numbers write the color word on the bottles. Sort pom-poms by color. Empty each bottle and count the pom-poms. Then record how many pom-poms were in each bottle. Add the two colors together for addition practice.
Counting and Measuring with Lego: Preschool Maths Game - Good way to visually compare numbers - I would suggest making the corresponding numbers (like 5 and 15 or 8 and the same color to help see the pattern relationship between the numbers and 15