When measuring length with a ruler, line up the object's left end exactly with the ruler's 0 mark. Then read the number where the object's right end touches — that's the object's length in cm. Use the slider to stretch and shrink the object, and practice reading the scale with the quiz.
Move the object length slider. The object's left end is always lined up with the ruler's 0 mark. Read the mark where the right end touches to find the length.
Object length8 cm
Count the marks to guess how many cm long the object on the ruler is. Type in a number and press "Check."