Mechanical pencil applied at an angle. When excess vertical pressure is applied on the lead, the lead is automatically retracted inwards. Higher-end mechanical pencils often feature a lead hardness grade indicator and sometimes feature a retractable lead guide pipe. This allows the lead guide pipe to retract back into the pencil body, which will keep it protected in storage and during transit and makes it 'pocket-safe'. In spite of the name, pencil leads do not contain the toxic chemical element lead, but are typically made with graphite and clay, or plastic polymers. Compared to standard pencils, mechanical pencils have a smaller range
Lead–crime hypothesis from other indicators of poverty such as poorer schools, nutrition, and medical care, exposure to other pollutants, and other variables that may lead to crime. Lead is a naturally occurring metal of bluish-grey color that has been used for multiple purposes in the history of human civilization. Being soft and pliable, as well as resistant to corrosion compared to other metals, has resulted in lead being used for many different items across time. Some of the earliest items made from lead were beads and jewelry dating back to 7th millennium B.C. Its malleability made lead an ideal choice for the