But for students that aren't used to figuring out how they'll investigate something, it's a tough question to put to them. They have been conditioned to want steps to follow, they want contant re-assurance they're doing it "right" and they want to know that they'll find the right answer.
What kind of comment is that to a science class? It's the best advice that I can give them. Because it's OK to try something and not have it work out the first time. Despite lots of read alouds that tell the stories of scientists working for years to have "something come out right", students don't think it all that trying applies to them. They believe that they should follow the steps I give them and it will be perfect.
So imagine how freaked they were when I asked them to show that air has mass...giving them only balloons, meter sticks, string and tacks. It's as close to inquiry science as I dare to go at this point because I can't set them loose to find everything on their own. Even with this help they were frustrated and confused. They talked and fiddled. I asked them leading questions. Eventually one by one, each lab pair figured out something to try.
It just took one or two pairs to be brave and try something. Bravery spread throughout the room and soon everyone had some idea they wanted to try out. I tapped into that kindergarten curiousity and boldness. And try they did....all sorts of contraptions to test out their ideas if air has mass. Some were trying to figure it out in buckets of water, some with balloons and string, and some built some very elaborate scales/balances.
I never did figure out how this proves that air has mass, but I'm determined to go back and listen to them explain it to me again tomorrow. Ask more questions and see if they have something that my head just doesn't comprehend.
This measuring device stayed up better and the student attached the balloons using string loops. It was a clever way to control the balloon and be precise about how far from the ends she was putting the items she was measuring.
It took this lab pair almost the entire hour to build their scale. Then they had to figure out how to overcome the problem of putting a deflated and inflated balloon on the balance at the exact same time. Needless to say, you had to be quick if you wanted to see their experiment. But I give them all props for perserverance and effort....plus they did demonstrate that air has mass.
Air does have mass....I can attest to seeing many lab pairs successfully demonstrate this.
And more than that, I think students had a learning experience where tinkering with something to try and make it work was OK. I had them record any modifications they made to their original plan on their lab sheet....and we'll talk more about if not getting it "right" on the first try is wrong....or is it a first attempt.
I think that will be the hugest (and I don't even know if it's a word but it applies to the learning situation here) thing I could teach my students. Go for it. Make a reasonable stab at creating something you think will work....learn from what happens....regroup....redesign....and go again.
Until you can show that air has mass. :->