March 25, 2017

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THE WOOLY WORM HUNT is an exciting "game" where the students are the Predators, hunting the great (and desirable) wooly worm. The class is given 60 seconds to pick up as many colored wooly worms as possible from the 1400 worms scattered across the Prep's front lawn. The 14 varieties vary with colors like white, neon pink, yellow, peach, teal, green and brown. Some varieties survive the onslaught of the dreaded "grey shirt" while others are hunted to near extinction. To test the hypothesis that there is preference for particular colors and that the wooly worms are not picked up randomly we use Chi Square analysis. This of course illustrates with greater than 99.5% certainty that earth tones are selected for and bright colors are selected against. The students are then asked to suppose that these are live, reproducing organisms and to predict what upcoming generations of wooly worms would look like. A really fun and interesting way to teach about Natural Selection

Wooly Worm Lab • The Chi Square Test:
If the wool pieces are collected randomly, then the number of each color collected should be nearly equal. Thus, a null hypothesis may be proposed that states that there will be no significant difference in the number of each color of yarn collected. If this null hypothesis is not supported by the data, then selection of some colors over others must occur. You use the chi square test to test this null hypothesis by comparing the number of each color of yarn expected to be collected against the number that is actually collected. The chi square value calculated from the formula is a measure of the variation from the expected values. The closer the expected and observed values, the smaller the chi square value will be and the more likely that the data is the result of random choice. Once you get your chi square value, you can use this number to estimate the probability that the null hypothesis is acceptable, i.e. that the wool was collected randomly without color preference. If the null hypothesis is unacceptable then the selection of some colors over others must have occurred. To get the probability look on the chi square distribution chart in the row with the correct degrees of freedom (# of colors

I did that lab above and I am stumped this question:given the current warming trend of our planet, over time (generations of parents and offspring) what do you predict will happen to the species of wooly worms?

  • science - ,

    See my response to your later post.

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