The 11 Best Toys For 9-Month-Olds, According to Pediatricians and Parents

The First Years Stack N Count Cups ($11)

Another great stacking option? These under-$10 cups. The bright colors are visually appealing to an infant, who will love the ability to fit the cups together or stack them on top of each other. Parents can use the numbers on the bottom to work on counting skills as a child grows. The cups have a 4.8-star Amazon rating based on more than 88K reviews, with parents raving that the cups are easy to clean, versatile, and durable.

"My son absolutely loves these stackable cups," an Amazon reviewer writes. "They've taught him a lot of different skills and has helped hone his fine motor abilities. The colors keep him engaged and intrigued."