I learned length.
First I learned the meaning of length. Length is something to measure the length of an object. I always measure from the longest side of the object. For example a book, the side of the book is the longest point so I measure from the longest point.
Next I did the length of a book, pencil, white board, chair, table, tote tray, and an object of my choice. The length of the side of the book I did was 35 cm, from the longest side of the book. Also I remembered to measure from the start of the ruler.