2. Supporting students to find patterns
Being able to think creatively and solve problems involves making connections and predictions based on knowledge and understanding. Many scientific discoveries have been made as a result of the creativity of scientists, and the invention of the periodic table is a very good example.
Learning about the chemical elements and the periodic table provides a good opportunity for students to practise making predictions. A good chemist can apply his or her knowledge of a few elements and chemical trends to predict the properties of practically any element. Case study 2 involves the teacher being resourceful and borrowing a laptop to show students pictures of the reactions. However, if you have access to the chemicals, you should try and show them the real thing. She differentiates the task by asking students of different ability to do slightly different things. Resource 3 has some general information on differentiation. The story of the periodic table demonstrates how scientists need to be prepared to take a risk and be bold. So in Activity 2 students hear the story of how the periodic table was invented and have the chance to make predictions just like Mendeleev did. Resource 4 has some background information to help you.
Case study 2: Patterns in Group 1
When she finished her training, Mrs Sam found a job in a secondary school near to Winneba University. When she was teaching her students about the periodic table, she borrowed a laptop from the university. She went to an internet café and downloaded video clips of the reactions of lithium, sodium, potassium, rubidium and caesium with water. She showed her students the clips of lithium and sodium and asked them to predict how the other metals would react.
She divided the students into groups according to their ability. She encouraged the group of students who found chemistry difficult to describe what they thought they would see in as much detail as possible, whereas she expected some of the other groups to write full chemical equations for the reactions. Later, she showed them the reactions of potassium, rubidium and caesium so they could see if they had predicted correctly.
The group of students who usually struggled with chemistry had done very well and produced accurate descriptions of the reactions. They confidently explained their predictions to the rest of the class. Later on, when they were revising the equations for the exams, even though they found them difficult, this group remembered the lesson and were very motivated to try and understand the equations.
Activity 2: Classifying elements
Divide your class into groups. Give each group a set of cards. Each card has some information about an element. Ask them to devise a way of classifying the elements based on the information on the cards. They will need to be able to explain how they have classified the elements and why they did it that way. After 15 minutes give them the chance to share their ideas with each other. Gather the class round the front and explain how Mendeleev worked out the periodic table (Resource 4). Tell them the properties of silicon and tin and ask them to predict the properties of the element that would fit in between them. Finally, tell them the properties of germanium and see how close they were. Explain that a good chemist can use their knowledge of the periodic table to predict the properties of almost any element.