In the last short video you learned about the size of the English vocabulary and how there are many words for the same meaning. A more serious vocabulary problem for ESL students is just the opposite, namely that there are also many words that have several meanings. The most extreme example is the word 'set', which has over 40 meanings. Here are just 4: A mathematical set, a TV set, a set in tennis, and set as in the sun going down.
The reason that this is a problem for learners is that they will often read or hear a word they know already, but which is being used with a new meaning to them. The name for a word that has different meanings is 'polysemous'. Here is a table showing some common polysemous words. The 'First meaning' column shows the meaning that the student is likely to meet first. The subsequent meaning is a less common meaning and is likely to be met later.
For example, students meet the word 'arms' as part of the body in their first days of learning English, and may subsequently be confused when they meet the word in a sentence about terrorists buying arms. They know 'subject' as referring to an area of study, so they don't understand it in the phrase 'subject to'; for example, that a decision is subject to change. 'Odd' is 'a type of number: 1 3 5 etc. ', but it also means 'strange or unusual'. And so on.
So, it is clear that you need to be aware of the difficulty of polysemous words for the Kalahari students. But this is not the only kind of word that causes problems.
The three blue categories listed here typically also cause significant difficulties, and are important for different reasons. The General Academic group contains words like 'arbitrary', 'propensity', 'rapid' and 'deteriorate' that are essential for understanding written texts and teacher explanations in all the subjects. Of course, students learning mathematics, geography, physics, and other subjects, will need to learn the vocabulary specific to that subject, such as these math words. But in most cases this vocabulary will be explicitly taught and learned, and is often the focus of the lesson.
On the other hand, general academic words like these listed here may occur in any or all of the subjects. The problem is that they are only very rarely explained by the teacher. In most cases general academic words express abstract concepts and are not used in everyday language. This makes them very difficult to learn in the natural way that students learn much of the other vocabulary. You need to be aware of this difficulty in the texts you read with the Kalahari students or what you say to them.
Idioms like the ones you see here are very common, especially in everyday English. They can be particularly difficult because the student usually understands all the words that comprise the idiom but has no idea what the sentence containing them means. There is no way, for example, that you can work out from the words alone that 'to be on cloud nine' means 'to be very happy'.
The next group of words, called phrasal verbs, are probably the most difficult category of vocabulary for English learners. Here are some phrasal verbs: 'to get at', 'to set off', 'to turn out', 'to put down', and 'to make do with'. As you see phrasal verbs usually consist of an extremely common short verb together with one or two prepositions (or particles, to be more exact). These words are very important because they are very common. And they are very difficult, because in many cases, like idioms, the actual meaning does not derive from the component parts. What makes phrasal verbs even more tricky is that many of them are also polysemous, so that even if the student has learned one meaning of the phrasal verb, there is no guarantee that it will be understood the next time the student meets it.
As an example, let's look briefly at the phrasal verb 'to put down'. In the first sentence it has the literal meaning of moving something down to a surface. In the second example it means to humiliate. In the third sentence it means to crush or quash and in the last sentence it means to kill.
Here are some more phrasal verbs. They may seem easy and obvious to a native speaker but they are certainly not for language learners; and you need to be aware of this when working with Kalahari students.