Monday, 10 October 2011

Blood Spatter

 Spent some time this week after watching season 1 reruns of Dexter:
From October 10, 2011

Showed the kids this, asked what the hell they thought he was doing.

I'd also seen this infographic over summer:

And we chatted about why a 10 degree angle of impact would leave a different shape etc.

Kids correctly surmised that it was related to the height/width of the droplet, so i dropped the formula on them, and we did some investigatin'!

After drawing some random blood droplets and swapping with neighbors, we jumped in and messed around in Geogebra creating the activity below (with some help from me in terms of the input aspect):

BloodSpatter - GeoGebra Dynamic Worksheet


This is a Java Applet created using GeoGebra from - it looks like you don't have Java installed, please go to
OG, Created with GeoGebra

Most entertaining if slightly bloodthirsty, led into using arcsin etc in trig very nicely.

We also created crime scenes that we could analyse, by drawing huge drops of blood on paper and tacking them to the walls, then going all Dexter with bits of string!

This basically works out the angle of elevation from the surface - not sure how we could find the "horizontal" angle to the surface though... Any thoughts?!