We had a lot of fun experimenting with the sun this week. Here's a look at what we did.
Experiment #1- Melting Ice in the Sun
Observation/Question: It feels hotter in our backyard than in our front yard... is it actually hotter or is the temperature the same?
Hypothesis: It is hotter in the backyard because it gets more sun. A tree in our front yard blocks the sun and makes it cooler. Ice would melt faster in our backyard (in direct sun) than under the tree in our front yard.
Experiment: We filled two identical cups (leftover from an Easter egg dying kit) with exactly the same amount of water. We froze both and put one cup of ice in the front yard under the tree, and the other in the backyard for about 3-4 hours.
Conclusion: The ice left in the front yard cup was bigger than the one left in the backyard cup. Our hypothesis was right- ice melts faster in the backyard. It is hotter in the backyard.
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Experiment #2- Sun Dial
Observation/Question: Can the sun be used to tell time and determine direction?
Hypothesis: The sun rises in the east and sets in the west everyday. We can use the sun to find North, South, East, and West, and to tell time. (Sam's hypothesis was that we wouldn't be able to tell time using the sun- he didn't give a reason why).
Experiment: Make a Sun Dial and observe it for two days to see if a shadow will appear in the same place at the same time for two days in a row.
I kind of screwed this experiment up. We didn't get out very often to make new marks, and I taped it down in a bad place... the shadow from our neighbor's garage made it too hard to see our pencil shadow at certain times during the day. But we were able to compare the shadow at 1:10 each day and see it was in the same place each day.
I also tried to teach them how to find North, South, East and West based on the sun dial, but it was a little beyond them. We just left it at the Sun rises in the East and sets in the West.
Conclusion: The shadow from the pencil was in the same place at the same time for two days. You can use the sun to predict the time.
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Observation/Question: The sun makes our backyard hot. Could we use the sun's heat to melt chocolate and make s'mores?
Hypothesis: On a hot, sunny day, chocolate and marshmallows will melt from the sun's heat.
Experiment: We made a solar oven to trap the sun's heat (on a warm, sunny day) and melt the chocolate and marshmallows.
We made sure the solar oven was always directed at the sun.
Sam pointed out that we could use our sun dial to position the s'mores. Without any prompting from me, he observed that the pencil shadow was pointing directly at our solar oven. He figured out that the sun must be shining in that direction to cause the shadow! So when we went out to check on our s'mores, we would position the oven so that the pencil shadow pointed right at it.
Conclusion: It took about 2 hours to melt the chocolate and warm the marshmallows. The sun's heat can be used to cook!
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Experiment #4- Green Grass Investigation
Observation: There was a square block of wood sitting in our yard for a few weeks. When we removed the wood, that square patch of grass had turned yellow.
Hypothesis: Grass is a plant, it needs sun and water to live. Our grass turned yellow because the wood blocked it from getting sun and rain. Now that the wood has been removed and the sun and rain can get to it again, the grass will turn green again over time.
* Sam said that he thinks it will turn green again, but it will take a really long time.
* Daddy said that he thinks some patches will turn to dirt before turning growing back green.
* Max said he thinks it will turn green.
Experiment: We outlined the yellow patch of grass with blue spray paint. We will watch it for two weeks to see if the grass stays yellow or if it turns green again inside the blue square.
Conclusion: Most of the grass was still yellow after two weeks. A small patch turned green, and some patches were just dirt.
*Max's Conclusion: Daddy's "hyposisis" was right. It turned to dirt.
* Sam's Conclusion: Everyone's hypothesis was a little bit right.
|Sam's Science Investigation Notebook entry for the grass experiment.|