1. Warm up- In 3-5 sentences, write what you know about volcanoes.

2. Effect of silica on volcanoes
The amount of silica (SiO2) controls the viscosity, or the resistance of a substance to flow. The higher the silica level, the more viscous the magma is; therefore, the volcano eruption is greater and more explosive. 

3. 3 types of volcanoes
Shield, cinder cone and composite volcanoes

4. Types of volcanoes
Shield- large volcanoes that are built almost entirely of fluid lava flows. It has broad sloping sides and is usually surrounded by gently sloping hills in a circular or fan shaped pattern, that looks like a warrior's shield

5. Types of volcanoes
Cinder cone- Cinder cone volcanoes are the most common kind of volcanoes hey are steep sided cones of basaltic fragments and are smaller and simpler than composite volcanoes. Streaming gases carry liquid lava blobs into the atmosphere that fall back to earth around a single vent to form the cone

6. Types of volcanoes
Composite- Sometimes called Stratovolcanoes, Composite volcanoes form when runny lava escapes through a fissure and flows a long way. Composite volcanoes are tall cone-shaped mountains that are typically steeply-sided, symmetrical cones of large dimensions. The essential feature of a composite volcano is a conduit system through which magma from a reservoir deep in the earth's crust rises to the surface. The volcano is built up by the accumulation of material erupted through the conduit and increases in size as lava, cinders, ash etc. are added to its slopes.

7. Activity

8. What effect does silica have on volcanoes?
Ending question
What effect does silica have on volcanoes?