|  | | Home > Junior High Classrooms > 7th Grade > Mr. Lewer-Science > Week by week |  | | Week 4: 9/22 - 9/26
OK, so here’s the deal: if we can figure out the characteristics of living things, and if we can list the requirements of living things, then maybe we can figure out the meaning of life! Want to give it a try? (Hint: it’s not 42!)
So, if you were on my spaceship and I beamed you down to a planet somewhere in a galaxy far, far away…would you recognize life if you saw it? What would you look for and how would you know that what you saw was alive? Can we make a list of the characteristics that you would use to identify a real living thing?
What do living things need? Can you make a list of the things that all living things need? Is there a list of needs that all living things have in common?
We'll dive into these deep thoughts this week and we'll finish making the tools that scientists use to make good, quantitative measurements.
Every measurement should have two parts: a number and a unit. The number tells us "how much" and the unit tells us "of what." How much of what - that's a number and a unit. The units we use are meters (length, width, etc.), and liters (volume = how much space inside an object), and  | | Directions for making the liter cube. Click on this image to enlarge. |
grams (mass, or weight on this planet).
Did you know that mass and weight are not the same thing? Your weight would change if you went to the moon where there is less gravity, but you would still have the same mass (hopefully!).
Weight measures the pull of gravity by  | | More direction to finish making the paper liter cube. |
stretching or compressing a
spring. Mass measures the amount of matter in an object by balancing it
on a teeter-totter with standard little mass thingys.
Ok, so we said that science is just a way of making up your mind based on evidence and logic, but evidence is gathered by  | | Templates and examples of the liter and the cubic centimeter. |
our five senses and the optical illusions reminded us that our observations could be improved with tools of measurement. That is, 96 miles per hour is a better testimony in court than "really fast."
We even fooled our sense of touch when we had our hands in cold water and the  | | Follow these direction to make a balance! |
room temperature water felt warm, but after we had our hands in hot water the same room temperature water felt cool!
Obviously we need measurements with numbers attached!
The other thing we discussed about measurements was a bit more complicated. Are you ready  | | Directions to finish building the balance. |
for this? Every measurement tool we use has lines on it with numbers, but almost always the thing we are measuring is a tiny bit between the smallest lines on our tool. So we make a guess about how far in between the smallest lines the measurement is! We do this in decimals, not fractions,  | | Hey, this this is really sensitive! It is accurate to 10 mg and detects 1 mg! |
and we include it in our records. So, the last number in a good scientific measurement is a guess, in the next decimal place, beyond all the numbers which there are lines for. This tells us whether there is uncertainty in the thousandths place or the hundredths place - whatever the  | | The hand made meter, liter, milliliter, balance. |
smallest lines are, the next number is a guess.
Whew! Did you get that? The rule is this: Write down all the numbers you are sure of (because your tool has those marks) and one more decimal place that is a guess.
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