Hardness
Science Lesson Description
In this lesson, students will learn about hardness as a property of materials. The students will build on their previous learning about everyday materials from years 1-4. In year 1, students identified and named a variety of everyday materials, in year 2 they found out how shapes of solid objects can be changed, in year 3 they compared and grouped different rocks, and in year 4 they compared and grouped materials into solids, liquids, and gases. This lesson is not part of the Year 6 Chemistry curriculum. However, it is linked to cross-curricular subjects such as History, Design and Technology, and English.
The main activity in this lesson is to produce a report on the Mohs scale and classify items based on their hardness. Students will use the Mohs scale to identify minerals in the field and it goes from 1-10, with the higher number indicating a harder mineral. Talc is 1 on the scale and diamond is 10. In the materials classification activity, students will use their own scale to classify items based on their hardness and write descriptions of the properties of each material. Finally, in the activity on the hardness of materials, students will physically test the hardness of various materials using a glass slide, copper coin, paper clip, fingernail, and other materials. The properties of the materials studied will be linked to their use, such as rubber being stretchy (elastic), making it ideal for elastic bands.
Misconceptions and Keywords
The lesson will address common misconceptions such as all metals being solids at room temperature and all metals being hard. It will also introduce keywords such as hardness, Mohs Scale, mineral, flexible, elastic, stretchy, and brittle. Influential scientists such as Alexander Parkes, John Wesley Hyatt, Leo Baekeland, Eugen Bauman, Wallace Carothers, and Friedrich Mohs will also be mentioned in the lesson.
Important Lesson Guidance
There is flexibility in the materials that can be tested in this lesson and the results tables are just examples. It would be best if a wide range of materials is available for the students to test for hardness, including rocks. There is also much flexibility in terms of the size of the groups, with the recommended group size being 4 students. The students will use learning pads for the Mohs scale activity.