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# news & tips

A collection of helpful articles on teachers and teaching

# High & Low Number Sense

All my students are fascinated with records, highs and lows. I think this would be an engaging way to teach some number sense in science.

I am amazed at the flooding in Australia this week. The human toll that a month of flooding must take is beyond comprehension. As my students watch this, they wonder if that is a global record. That is a good place to start an adventure on the web that takes us to some amazing global facts.

I am fine with pursuing facts just for the intellectual stimulation but like you I have content in science to manage. Some of the concepts that my students have difficulty with are accuracy, precision, and significant figures. You have encountered this lack of number sense when your students give you answers that have a running series of 8 digits beyond the decimal. The rule is that you can only report an answer that has the same number of significant figures as the number with the fewest significant figures.

You may want to refresh your memory about what a significant figure is. Well, any non zero digit is significant and zeros are only significant if the fall between two non-zero digits (3.0045 has 5) and if the zeros are trailing a non-zero number and there is a decimal they are generally significant. So, 2,000 has only one but 2,000.0 has 5.

Ok, with a bit of a refresher in place how do you use records to help teach this stuff? We started with temperature records. They usually report the temperature without any decimals like 9 degrees or 32 degrees. Some meteorological sites report average temperatures one decimal place more (32.1 degrees). It is good to ask the kids where a more accurate temperature might be needed. Some will say. This should prompt a good discussion as there are few common temperatures that need to be reported more accurately than a tenth of a degree. The payoff here is that you are getting your kids to think science and applications.

We report flood stages in feet and rainfall in inches. Why the difference. This site give you access to all sorts of weather data that should inform this discussion.
http://www.worldclimate.com/

Since the world measures in metrics and the United States does not universally use the same units it is a great time to talk about conversions. These two sites do an exceptional job of guiding conversions. I do steer clear of those sites that just convert numbers automatically. I really do want my kids to know how to convert.
http://www.amadeus.net/home/converters/en/area_en.htm
http://www.purplemath.com/modules/metric.htm

One of my favorite journeys to highs and lows was gas prices. My students found out that regular gas was about 36 cents in the 1970’s. In their lifetime gas will probably hit \$4.00. We measure gas at the pump to the fraction of a gallon. What if we went one digit further? Would it save us money or cost us money to measure more accurately? That will require a bit of thinking.

Some other interesting applications of high and low numbers include longest rivers (good connection to geography), heaviest animal (and lightest), largest and smallest plants, and fastest and slowest growing plants.
http://www.worldatlas.com/geoquiz/thelist.htm
http://www.enotes.com/science-fact-finder/animal-world/what-largest-smallest-living-animals
http://waynesword.palomar.edu/ww0601.htm

So, as the snow files in the Midwest and the inches of the white stuff are now being measure in feet you can use that interest in numbers to help teach some helpful science number literacy.