The relationship between meters and centimeters: 1 m = 100 cm, 1 cm = 10 mm, 1 m = 1000 mm.

When measuring short objects, we usually use millimeters, centimeters and so on. As a unit. For example, the width of the eraser is 2 cm and the thickness of the pencil lead is1mm; When measuring long objects, we usually take meters and kilometers as units. For example, the length of a playground circle is 400 meters, and the designed mileage of a bus is 15 kilometers. Method of measuring the length of an object: aim the left end of the object at the "0" scale of the ruler and see what the scale of the right end of the object is on the ruler. The length of this object is several centimeters.

Fill in the appropriate length unit:

1, Xiaoming's height 1 (m) 30 (cm).

2. Xiaoming's height 130 cm.

The width of the exercise book is 13 (cm).

The length of the pencil is 17 (cm).

This blackboard is 2 meters long.

6. The length of the pushpin is 1 (cm).

7. A bed is 2 meters long.

8. A well is 3 meters deep.

9. The school held a 100 (meter) race.

10, the teaching building is 25 meters high.

1 1, and the baby is 80 (cm) tall.

12, skipping rope is 2 meters long.

13, a tree is 3 meters high.

14, a key is 5 cm long.

15, a pencil box is 24 (cm) long.

16, the podium is 90 cm high.

17, door height 2 (m).

18, classroom length 12 (m).

19, chopsticks are 20 (cm) long.

20. The height of a small sapling is 1 (m).