1. Observations is a statement of FACT. You must use one of the five senses. An inference is an OPINION based upon prior knowledge.

2. Inference or Observation?! 1. The hawk has brown feathers 2. This pebble is round because it was rolled down a mountain 3. This plant has thorns down the stem 4. The girl is sad because she is crying 5. Tomorrow it is going to rain because it will be cloudy.

3. DENSITY OF OBJECTS DO NOT CHANGE! If you have a piece of wood with a mass of 20g and a volume of 10cm 3 Density of this object is 2 g/cm 3 What if the wood is cut in half? (m = 10g volume = 5cm 3 ) Density STILL equals 2g/cm 3

4. Which one is more dense? Demonstration: People in a square How about this: Which square is more dense?

5. What is density? Density = mass OR mass ÷ volume. volume Units for density: g. cm 3 Why are these the units for density? ALWAYS REMEMBER UNITS!

6. Let’s try a density problem together Frank has a paper clip. It has a mass of 27g and a volume of 9cm 3. What is its density? Frank also has an eraser. It has a density of 5g/cm 3 and a volume of 1cm 3. What is its mass?

7. Work on these problems with your neighbor. Jack has a rock. The rock has a mass of 64g and a volume of 2cm 3. What is the density of the rock? Jill takes the rock from Jack and drops it. The rock is now in two pieces. What is the density of each piece of rock?

8. Liquid Layers Which layer has the highest density? Which layer has the lowest density? Imagine that the liquids have the following densities:  10g/cm 3.3g/cm 3.  6g/cm 3.5g/cm 3. Which number would go with which layer?

9. Liquid Layers – Try with your neighbor Which liquid has the highest density? Which liquid has the lowest density? Which liquid has the middle density?