## Reflection: Rigor Bonding Inquiry - Section 4: Evaluate

I really like this lab and have been doing it for years, but I feel that every time I do the lab I find ways to improve it.  This year was no exception and I have several ways I will change it for next year:

1. For Station #2 a lot of students got confused because of my wording for the test information: "Crystal structures form from the interaction of positive ions (cations) and negative ions (anions). If it does not have a crystal structure, then it usually just has anion."

I was trying to have students see that crystals get a shape because of the cations and anion, but I think that this was too confusing.  Rather, i will go back to what i had in previous year and just have:"A crystal structure is composed of a set of atoms arranged in a particular way, which is repeated in three dimensions on a lattice.  So crystals will tend to have a specific, repeating shape."

2. For Station #8 some students do not understand how to find the difference.  I need to make sure to have an answer for the example on the Test Information part of the station:

For example: CaCl2

Ca: 1.00  Cl: 3.16    The difference is _2.16___

3. In the conclusion I was trying to keep the claim and evidence wording through the sentence starters:

In this experiment, it was discovered that __________________.  Three examples of data and evidence from the experiment that support this claim are ______________.

Many students were not sure what to write for what was discovered.  I was just trying to get them to write that ionic and covalent compounds have different characteristics.  And then for the three examples use information from three of the eight stations.

For next year I will start the conclusion for them with: "In this experiment it was discovered that ionic and covalent compounds have many different characteristics.  Three examples of claims concerning these characteristics which I found in this lab, and the evidence that support these  claims include ___________________________________"

Here is a copy of the updated lab which I will use next year.

Rigor: Changes for the lab

# Bonding Inquiry

Unit 3: Unit 3: Bonding & Periodic Table Trends
Lesson 2 of 9

## Big Idea: Ionic and covalent compounds have different chemical and physcial properties.

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55 minutes

### Rachel Meisner

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