Student Led Science with Chemical Reactions

As a precursor to chemical reactions, allow students some time to experiment with pH indicators, discuss the periodic table and chemical formulas, and take some time to do at least one teacher led chemical reaction such as a baking soda and vinegar explosion in a ziplock bag.  Also, discuss the differences between a chemical and physical reaction.

Now this is how I allowed students to do their own chemical reactions…

*Students were able to choose what substances they wanted to mix.

*They were able to choose five reactions to perform.

*Students worked in groups of two.  If they couldn’t settle on what to mix, I told them that they could choose two and their partner could choose two reactions.  The last reaction they could do all alone.

*Students predicted what would happen in each reaction, and then recorded the results.

*I posed this question to the students before they began, “Will acids and bases always create a chemical reaction when mixed?”

Students were able to choose from the following substances to do their reactions:

1. cream of tarter
2. borax
3. baking soda
4. vinegar
5. Sprite
6. dishwashing liquid (watered down a bit)
7. lemon juice

I used these little artist’s palettes with circular indentations in them for students to mix substances. These palettes were numbered so that substances could be numbered.  I also had these little medicine cups that came with a science kit.  The cups hold about one ounce.  I had the different substances already poured out for students to use.  Students could only get one cup of each substance, and if they were using the same substance for more than one experiment, they had to use that one cup for both experiments.  The little spoons you see worked out very well.  A colleague was getting rid of them, and I gladly took them off her hands.

This is further how I organized the materials at the supply table below.  Again, this is not a beautiful blog picture, but it is real life after several classes had experienced this activity.  I had different pieces of paper to organize the substances with the name on them.  I told students they had to manage how to organize them at their own desk.  In the picture above you can see that these students were very organized when they got to their table.  They labeled their cups on notebook paper.

After students experimented many of them wanted to further mix what was already on their experimenting plate.  I allowed this, but required them to write down what they had mixed.

In closing discussion, we talked about what happened when different students mixed different substances.  We talked about whether these substances created chemical reactions, and students had to give evidence for a reaction being a chemical reaction.  For example, did the substances produce gas, change temperature, or did they turn into completely different substances?

The students really enjoyed this learning experience, and this spurred them on to experiment at home on their own.  I encouraged them to experiment over the summer especially because most of these substances can be found in the kitchen cabinet.