Hoover Dam

I interrupt our Denmark Unit to bring you this special coverage of the Hoover Dam. Would you believe me if I said the boys were just as excited about going to the Hoover Dam as they were about going to Disneyland? Our trip to Flaming Gorge just whetted their appetites (the Flaming Gorge guide kept giving stats in relation to the Hoover Dam), so they'd been looking forward to it for a long time. Unfortunately, kids under 8 can't do the longer tour at the Hoover Dam, but we did get to see the powerhouse and everyone seemed content with that. Junie was extra heavy and squirmy and we hadn't brought the stroller, so Sam and I were definitely content with that!

Seb loved this huge wall diagram of the path of water through the powerhouse and dam. Probably because he has drawn many a similar diagram, in his day.

Tunnel toward the old diversion tunnel

The enormous penstock---we got to walk right over it

Powerhouse (Nevada side)---7 of the 15 enormous turbines

Intake towers

Outside 

One of many re-constructions created after we got home (note powerlines coming out of powerhouse toward transformers)

Hydropowered "Generator"

Well, frankly, this was a little disappointing. When I was preparing to teach about hydropower and generators, Sam said, "Why don't you build a generator?" I didn't think I could handle helping the boys do that by myself (I'm just barely learning how they work myself!), but the more I thought about it, the more I thought the boys would get really into that idea, so I finally found some instructions that seemed detailed enough for even me to follow. They had pictures and a supply list and everything. The hardest part was finding copper magnet wire, which the instructions acted like could just be picked up at any old store. Home Depot and Lowe's didn't have any of this gauge (very small---24), and neither did Radio Shack, where they sent me. I finally ordered it from Amazon, which I should have done in the first place.

The rest of the supplies were mostly things we already had, or fairly easy to come by, so we set aside an afternoon to work on it. Seb and Abe (the only ones I really thought could participate) were SO excited. We wound and wound and wound until we had four coils of wire. But then things started to be complicated. We didn't have quite the right size cork, or quite the right size dowel, and we tried to make it work but we weren't sure if it was going to. And our current, when we tested it, was definitely doing something . . . but we couldn't quite tell if it was doing what it was supposed to do.

Anyway, the long and the short of it is, the turbine turned beautifully (with enough water pressure, e.g. the hose) but we couldn't tell if it was actually generating any power for us or not. The tiny flashlight bulb we tried to hook up didn't light, but we weren't sure if that bulb would even work with alternating current, and then our multi-meter didn't get consistent readings, but we don't know if that's because we didn't have good contact with the wires (hard to hold it still when you're trying to hold the hose on the turbines) or because the current wasn't running. There were just too many variables. Was the incorrect dowel size causing trouble? We couldn't see why it would be, but who knows? Did it matter that I put the turbine in the bottle upside down (yes, that was my stupid mistake) so we were sending in the water from the bottom instead of the top? I just don't know enough to decide what matters and what doesn't.

After spending so much time building the thing, we were quite sad not to know if was actually working or not! However, the upsides were: 

• it was cool making the turbine spin---the boys loved that, and it was impressively fast and powerful (better than our paper cup waterwheels).
• it was pretty fun to build---we liked wrapping wire and cutting spoons and so forth
• we really got a solid understanding of the parts of a generator. You always remember things better when you've handled them and worked with them; so now, for example, the boys don't forget which part is the stator and which is the rotor, or which part has the magnets, or why the turbine has to be attached to a shaft that turns the rotor, etc. I feel like I truly grasped those concepts for the first time as we were making it.

So I wouldn't say it was a waste of time, and I do think it was probably our mistakes that caused us to go wrong, not the instructions---they were pretty clear. (Though perhaps they could have been slightly clearer . . . ) This is a project we may attempt again later, when I've recovered from this time. :)

Flaming Gorge Dam

The culmination of our study of dams was a trip to Flaming Gorge Dam in Eastern Utah. Upon looking up our route on the map the day before we left, we were excited to see there would be two other dams and reservoirs along the way! The boys were looking out for them with their beady little eyes the whole time we drove. Here is the first, a small embankment dam called Mountain Dell, I think?

So lovely in the morning light!

And the next, also embankment, was Echo Dam and Reservoir. The water level here was really low!

We were also pleased to spot lots of windmills as we drove!

Flaming Gorge itself is gorgeous! (ha ha) It goes on for miles (we didn't nearly drive around it all)

We enjoyed driving across this bridge as we got close

From the top, the dam isn't that huge---I assumed the water wasn't that deep, maybe 100 feet or something. But once we got around to the other side . . . 

we could see that estimate was way off! I think our guide said it's 500 feet high. It's even a bit longer from side to side than Hoover Dam---though much, much shorter in height!

It was so exciting to see all the parts of the dam---we could hardly believe that the tour let us go into the powerhouse and see the generators at work! The children were SO curious about everything (the guide said she'd never seen children like them---er. . . I believe her exact words were that they were the "most dam knowledgeable" kids she'd encountered on this tour. Ha ha. :))

Power lines. It was stormy, and not too comforting to hear another guide tell ours as we left for our tour, "Just make sure you don't get hit by lightning!" This impressed the children greatly, and when they asked if the dam had been hit by lightning before, our guide replied, "Oh yes---lightning has hit the dam, the powerlines, the visitor's center---we all ended up on the floor after that one!" It added a delicious thrill to our visit.

Looking down

Sluice gates, leading to the penstocks

Inside the powerhouse---three big generators!

Malachi. That dark grey shape in the background is an old turbine.

Looking up from the bottom

These were interesting---hollow jet valves, I think they were called? They're an alternate release system, in addition to the spillway. They can bypass the turbines and let water out here if they need to work on the generators or release water pressure a bit. Our guide said these were in use all last summer. The spillway (not pictured---it's higher up), on the other hand, has only been used once, in 1983!

Here's the end of one of the diversion tunnels they used while constructing the dam

Reservoir from above

And, looking the other direction, the top of the dam

It was a great field trip, well worth the long drive and the late night getting home---especially since we got to enjoy views like this as we drove!

Building dams on beach

We were really excited to get to studying dams, because that was one of the whole reasons we did this unit: the children (especially Seb) love dams! Our previous study of water pressure and waterfalls and mills made it really easy to understand the potential energy that can build up in a head of water. We drew lots of diagrams of how dams work:

One of Seb's diagrams

I wanted to have the children make a dam, but wasn't sure where to get enough sand/mud to make it fun. Finally realized the beach would be perfect (we brought some of our own gravel and big stones to use with the sand). It was so fun to watch all the different models everyone came up with, and the modifications they made as they discovered what worked and what didn't! Next time we will also bring large tongue depressors to use; I saw a video using those and popsicle sticks, and it looked like they worked quite well.

We did have one casualty to this activity: my large square rubbermaid container, which apparently floated out to sea. Other than that, we had a great time! :)

Such busy workers!

Junie was quite, some would say TOO, brave and independent at the beach. She went everywhere! When she spied these ducks, she took off like a shot after them, quacking frantically as she went. I had to run to catch her so she wouldn't follow them right into deep water!

"You are not a duck!" I said, and this was her sad response.

This was quite an effective dam---using my good cake pan, of course

Directing the flow

Is this baby wearing brown leg warmers?

This was another day---we built an arch dam with clay and cardboard, to measure the strength of different arch arcs (?) and determine which type of arch held the most water before failing. Very interesting.

One night this week we also watched David Macaulay's documentary Building Big: Dams. It's excellent; one segment of a 6-part series which we hope to watch the rest of sometime. We got it on Netflix.

Water Pressure

I don't have a lot of pictures, but understanding water pressure is essential to understanding how dams and water towers and pipe systems work, so we had a lot of discussion about it (and, peripherally, air pressure). Along with the bottle demonstration pictured above, the older boys were delighted to play this trick on Sam. We also used Sebby's straws (he got these for his birthday a couple years ago) to experiment with the ways that pipe thickness, distance, gravity, etc. affect water pressure.

They took their hole-y water bottles outside and pretended they were water towers (enterprising Abe, whose bottle worked fastest, was charging "money" for the others to fill their cups at his water tower)

We talked about clouds and rain and lightning on one of the days (just briefly; we will do a longer unit on weather sometime because there's lots more to cover!), and made these clouds in a bottle. We also loved making "lightning" with balloons and light bulbs (as described here and here). We did this demonstration in my closet and the kids LOVED it. They were all giggly and nervous there in the dark at first, not knowing what would happen, but after we made it work a few times, they could hardly be persuaded to stop! [note: We used a CFL and I thought it looked much more impressive with that than with his long fluorescent bulb in that second link, but I do really like his explanation of volts vs. amps and how fluorescent bulbs work. ]

A couple other good resources we used on water and air pressure:

http://thehappyscientist.com/science-experiment/feeling-pressure

http://www.asme.org/kb/news---articles/articles/k-12-grade/5-ways-to-demonstrate-air-pressure-to-children

http://thehappyscientist.com/science-video/cartesian-diver

http://www.history.com/shows/underwater-universe/videos/the-science-of-water-pressure#the-science-of-water-pressure

http://www.abc.net.au/spark/experiments/s1199904.htm