Prequel: Max's Vocabulary Acquisition.

After tracking the vocabulary development of all 1000 words Max learned to say before his 2nd birthday, I was required by Hacker Dad Law to follow up with the same experimental protocol for his brother Clark. I tracked from the very beginning this time and went to 2.5 years old, by which point Clark had 792 words. The graph:

Out of the 792 words, he knew 582 English words, 205 Chinese words, and 5 words in other random languages. Most of the Chinese words came from me, as I still spoke mostly Chinese to him, and he got some at daycare. He got some English at daycare, from Chloe, from Max, and from me whenever I lacked discipline and lapsed into English. This is basically the same environment and also same language ratio as we saw with Max.

The kinds of words he knew:

In comparison to Max, I noticed:

• He learned fewer words, also demonstrating some plateaus in learning, whereas Max had smoother vocabulary growth.
• Comparing Clark's 792 words at 30 months to Max's 1000 words at 24 months, Clark actually learned more total verbs, people, adjectives, numbers, letters, times, directions, pronouns, prepositions, determiners, emotions, particles, shapes, classifiers, and conjunctions. But, the total vocabulary was lower, because Max learned far more objects, foods, animals, body parts, exclamations, vehicles, colors, and sound words. A lot of the words Clark learned that Max didn't were parts of sequences (especially letters, numbers, and songs), and it was easy to observe Clark's obsession with those, versus Max's eagerness to point at and label nouns.
• Clark picked up reading earlier than Max, in this age range, and was even more engaged with books. But, this didn't translate to increased spoken vocabulary.

If you want to see the full words, play around with the data, or do a similar vocabulary tracking project of your own, here's the spreadsheet: Clark's Vocabulary Words

This post is a little behind the times, as Max is now 5.5 and Clark is now 3. At some point, I'll follow up with more on their progress in related areas like reading and coding, which are interesting given how much they've been able to learn with a very small amount of highly efficient practice.