Children may learn new words better in the context of other words they have just learned. It seems counter-intuitive, but new concepts seem to stick better when introduced among other new concepts than around older and more familiar ones.
Young children learn best through social contact and interaction with their environment. Talking about objects while picking them up and playing with them brings new vocabulary and ideas into toddlers' developing minds. The fact that little kids learn best by relating new knowledge to previous concepts is not new, but surprisingly, it's more effective with the previous concepts are fairly new as well.
A recent study found that children internalize new vocabulary better when words were introduced in the context of other newly-learned words. This was surprising to the researchers, who expected the toddlers to pick up new words more easily in the context of more familiar words that they had known for some time.
During the study, half of the children were introduced to two new words, which they reviewed until they had them down solid. Then a third new word was presented. After a coloring break, they were asked to repeat the third word. The other half of the children also learned the third word, but in the context of familiar objects. After the coloring break, they were less likely to remember the new word.
The data suggests that parents and early education teachers should teach new concepts in succession. Making connections and building on recently-acquired knowledge will help kids internalize what they learn. For example, parents might consider teaching the colors one by one, and then introducing things that are blue.
Parents don't need to make a plan for every little thing they're going to teach their toddlers, of course. This is more about making organic connections and building upon recent knowledge through play and daily life. And ultimately, talking to little ones and pointing out things in the world around them is what matters.