Visual aids can help understanding as well as retention.
Example
The class is learning vocabulary to name parts of the face and the teacher uses photographs of people as a visual aid.
In the classroom
Teachers can use pictures, video, symbols, gestures and facial expressions as visual aids.
Further links:
https://www.teachingenglish.org.uk/article/using-flash-cards-young-learners
https://www.teachingenglish.org.uk/article/graphic-organisers