I bought some of these containers for use in activities that aim to strengthen my son's pincer grip. He hated the other pincer grip activities I had him perform in the past, and although he was following the instructions, he was also whining the whole time: A-ha-ha-ha-ha-ha. Woe-hoe-hoe-hoe-hoe-hoe. Woe-hope! Peep-peeeeeeeeeep. Woe-hope! Oh-nen-nen, how-wha-way.
To fill the containers, he needed to first squeezing them to force the air out. He had to dip the container in the colored water, and then release the pressure so the liquid can get in.
He had to try several times before succeeding in making the liquid enter the container, but he persevered. I also observed that he had lots of difficulty manipulating the tiny lids, but he managed to open and close the containers. He tends to get frustrated easily, so I am amazed that he finished this activity without the need for the usual prompting and encouragement from me.