Goal(s): This lesson will teach students how to use the Moh’s Scale of Mineral Hardness to determine the hardness of various minerals.

Grade level(s): 4-5

Objective(s):

Students will be able to use the Moh’s Scale of Mineral Hardness to determine the hardness of various minerals.

Prerequisite(s): Knowledge of what a mineral is.

Standard(s): Earth, Space, and Science (3-5) 2. Identify the physical properties of minerals (hardness, color, luster, cleavage, and streak), and explain how minerals can be tested for these different physical properties.

Time Allotment: 1 class period

Focusing Question(s):

What do the numbers mean on the scale?

Material(s): (1 per pair of students)

minerals from previous lesson

wet rag

penny

dull butter knife

steel file

small piece of porcelain (with edges taped for protection)

Vocabulary: Mineralogist, Mohs Scale of Hardness

Procedure:

1) Students will be seated with their science buddy and told the objective. Students will be asked to recall the previous lesson on how to identify a mineral. Students will be asked to state some of the characteristics we look for when we are trying to identify a mineral. Students will be asked to recall that there is a sixth way to identify a mineral. Students will be given a brief history with visuals on the German mineralogist Friedrich Mohs and the Moh’s Scale of Mineral Hardness.

2) Students will be provided with the same group of minerals from the previous lesson. Students will be asked to recall that in the previous lesson, we talked about how we would be able to tell which of our rocks were the hardest. Students will be told that they will use some of those ways to actually test the hardness of their rocks. Students will be asked to develop a hypothesis that states which rock in their collection is going to be the hardest and why. Students will be given instruction on how to begin testing their hypothesis.

3) Students will be given 10-15 minutes to place their rocks in order from softest to hardest. Students will be asked to provide reasoning for their ordering as they work. Students will have the opportunity to walk around the room to investigate how each group of minerals were ordered by other students.

4) Each pair of students will then receive a set of supplies for testing, written directions paired with visuals, and a Moh’s Scale identification chart. Students that may have fine motor impairments will receive individualized assistance. ELL students and those that have difficulty comprehending written directions will receive an adapted version of the written instructions as well as verbal instruction. The chart and its numbers will be explained. Safety precautions will be reviewed. Students will be told that as they test each rock, they are to place the rock on the number that matches the tool marked by the rock. Each rock should then be cleaned with the wet rag to remove any small particles that may be hiding in the mark. A brief demonstration will be given on an overhead projector.

5) Students will be given 30 minutes to test their rocks. The class will then gather for whole group discussion to talk about their findings. The focusing questions will lead the discussion. The students will be asked:

 

a) Were you able to test your hypothesis? What were your conclusions?

b) Do you think your rock is really a mineral? How do you know it is?

c) Did you find out the name of your mineral? How do you know this?

e) What did the numbers on the scale help you do in this experiment?

f) Why did we not have na minerals in the class to test number 10 on the scale?

g) Where would chalk fall on the scale?

Assessment:

Students will be assessed according tho their participation in the experiment and the group discussions.

Students will be assessed according to their ability to use the Moh’s Scale of Mineral Hardness to determine the hardness of various minerals.

Extension(s):

1) Students could gather rocks from home or from the school grounds to test.

2) As a science center, students could participate in an on-going investigation of classifying rocks and minerals.