forensic style investigation activities

Hello all does anyone have any good ideas for yr 7/8 forensic style investigations? I would be grateful if you are able to share them please? I have just been notified that at end of November we are having a yr 7/8 taster day and will have 22 students in science each hour for the whole day. I have a few ideas but was thinking of maybe having 3-4 ideas that they can move around as a circus of activities. they will only have one hour to complete any activity.Thanks.
 

karen b

COMMITTEE
fingerprinting
chromatography of inks (who wrote the ransom note)
shoe prints in plasticine or make a plaster cast
fibre identification using a microscope
flame testing soil samples doctored with various salts.
blood splatter - what height was the blood at the scene dropped from. Takes a bit of prep
 
fingerprinting
chromatography of inks (who wrote the ransom note)
shoe prints in plasticine or make a plaster cast
fibre identification using a microscope
flame testing soil samples doctored with various salts.
blood splatter - what height was the blood at the scene dropped from. Takes a bit of prep
have you done the blood splatter one? how do you/they do this please?
 
Make fake blood
Blood recipe:
In 500 ml water
1,000g sugar
37.5 g cocoa or drinking choc powder
7ml red food colouring

Then use teat pipette to drop blood on A3 white paper from various heights measure diameter of spot. Graph the results

Also DNA extraction
fingerprints
 

karen b

COMMITTEE
Make fake blood
Blood recipe:
In 500 ml water
1,000g sugar
37.5 g cocoa or drinking choc powder
7ml red food colouring

Then use teat pipette to drop blood on A3 white paper from various heights measure diameter of spot. Graph the results
We set up stations with pipettes fastened to a metre ruler/clamp stand. They practiced on scrap paper then then had cm squared marked pieces of card to drop some blood on. They measured the diameter of each spot and drew a graph. There is a crime scene blood drop for them to measure and then use their graph to say the height it fell from.

This is with year 7 girls. the boys school down the road did something similar, but not so tightly controlled, and they got very creative with whether the blood fell at an angle. I think it looked like a blood bath after they'd finished
 
Can't remember who originally suggested testing for blood group but we've used it a couple of times and think it's pretty cool.

Use full fat milk with red and black food colouring for the blood, vinegar or lemon juice for a positive result (we use citric acid as it doesn't smell or have a colour) and water for a negative result. Make sure you use good quality milk, we found it worked better with Waitrose milk.

We do it as part of a cluedo type day. I made laminated sheets for each character with A, B and RHESUS circles on, each sheet has a dropper bottle of A, B and RHESUS "reagents", contents of each bottle depends on required result. Positive clumps pretty well.
 
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