What do you do in the spring extension practical?

First set up a clamp stand, two bosses and two clamps. Now place a heavy weight on the clamp stand to stop it falling over. Next, attach a spring in the first clamp and a meter rule in the second. Ensure the top of the spring is at the zero point on the meter rule. The meter must also be vertical to avoid inaccurate readings. And the bottom of the spring has a wooden split attached as a pointer, that must be horizontal to avoid inaccurate readings. Now read the position of the pointer on the meter rule. This is the unstretched position of the spring (the length with no force attached). Next hang a 1m weight on the spring. Read the new position of the pointer on the meter rule. Continue adding 1N weights on the spring and reading the position of the pointer. Then these readings to work out the extension