(Apr 21/April 22)
OBJECTIVE(S)
Experiment design
LESSON & ASSIGNMENT
D block: (1) Students do "salt & sand mixture" lab using their own flowchart. (2) Students record masses of salt and sand before and after mixing, and measure glassware masses. Record all data and find percent salt recovered and percent sand recovered.
F block: In the last period with this class I introduced an upcoming project and students may have questions about the project. Have students save their questions and address them to me directly tomorrow at school or on email or Google chat. Today's assignment is related to the project but it is of part of the project. This assignment is independent of the project.
1. Provide handout to students. They will need index cards or loose paper and some drawing tools. Most students are in geometry and have compasses and protractors so they are equipped for this assignment. I have some scissors for students to borrow, but they need to all be returned at the end of class. Students work in pairs with the person they sit with (no shuffling seats!) Each table should make at least 12 water molecule models. The angles of the bonds (as described in the handout) must be correct on student water molecule models. The names of both students in the group should be on the back of all their water molecules. Collect their molecules at the end of the period unless students want to use them at home-then they must bring them next class to hand them in.
2. Working in pairs at their tables (you may permit some to work on lab tables at the back of the room), students are trying to determine why water molecules give rise to hexagonal symmetry in snowflakes, based on the tendency of water molecules to stick to each other (their "polarity") and on the "bent" shape of each water molecule. Remind students that they may need more than twelve water models to find a clear pattern, in which case they should make more models.
3. When students have determined the relationship of molecule polarity and shape to snowflake geometry, then they should explain their hypothesis to you. if it sounds reasonable then they should find a way to communicate their hypothesis to me. They may do so in writing and drawings on paper; they may make a powerpoint; they may record an explanation using Audacity or other widely compatible audio format. If their computer is able, they may also make a video to show me what they are explaining. Although students work in pairs, each student must submit a separate product to me.
4. If students have papers to give you then collect them for me. If students are finished with their models, please make sure they have student names on the reverse of every model and paperclip each groups models together for me to see when I return.
Assignment:
F Block:
D block: