We have moved on to the immune system here. After reading the fantastic and very detailed book
Achoo by Trudee Romanek L started in on some fun experiments.
The first one involved the whole family. We cut up a piece of bread. The first piece we did not touch and put it straight into the ziplock bag as the control. The second piece the whole family got to touch with their dirty hands. L got to cough on it a bit and even dropped it on the floor for good measure. So much fun! Then we all washed our hands really well with lots of soap and touched the last piece of bread. L put them all in the bags and labelled them "dirty" "clean" and "control" with the date.
I forgot a crucial part to dampen the bread a bit before we sealed the bags. This made the process take a whole lot longer but eventual she began to see results.
The dirty bread started to grow some blue/green mould.
L recorded her observations. We concluded two things from this experiment. 1. Washing your hands really does make a big difference. 2. Store bought bread has a ton of preservatives in it. It took almost two weeks before we saw and change in the bread.
Next up we learned how food is metabolized in the body and how carbon dioxide is produced. L reproduced this effect by adding yeast and warm water to three different amounts of sugar.
As she added the water I placed a balloon on the top of the bottle.
After an hour this happened. The surprising thing is you would think the bottle with the most sugar would produce the most carbon dioxide but it actually turned out opposite in our experiment. After much Googling I was able to explain that the huge amount of sugar was too much for the yeast to eat through and therefore it couldn't eat as much or produce as much energy (carbon dioxide) this actually worked well to show how too much sugar is really bad for our bodies.
It also lead in perfectly to our follow up talk about refined and natural sugars and their effects on our body. L made up a list of food that she eats with good and bad sugars and she was surprised to find out that bread and pasta have glucose in them which is actually sugar and so does milk. It really helped to her evaluate how much sugar she is having at each meal.
After finishing up with the experiments and recording her results we talked about how the white blood cells figure out which cells are good and which are bad. L learned that they have receptors that match to specific antigens. Basically when the T and B cells have found a cell which is bad they destroy it but leave a few T cells around to remember it for the rest of your life.
We did an activity to demonstrate this. L found different objects around the house to be the antigens. Some were good cells and some bad. She made predictions whether these would be easy for the T cells to identify or hard. She then made an imprint of them out of clay. We hid the objects around the house and L took one imprint(receptor) at once going around searching for it's match and then decided whether it was good or she needed to destroy it. L realized that some items like the round lids could be mistaken for other things like a coin so they were bad matches.
This was such a cool way to understand how the white blood cells work and L absolutely loved it. After she tried it I made up some more imprints without her looking for a bit more of a challenge.
This activity also helped L to understand how vaccines work and why we get them.
