martes, 7 de marzo de 2017

Sundial Project

If you want to know what time it is, you probably watch at your wristwatch or mobile phone. But imagine that you live some centuries ago... Sundials are the oldests known instrument for telling the time. In fact, the earliest known sundial was made by Egyptians about 3.500 BC. As the Sun moves across the sky, the shadows objects cast move too. And people use this movement to know the time.
There are two parts in a sundial. One of them is called a gnomon; normally a stick that cast a shadow. The other one is a flat surface with marks, one for each hour of the day, where the shadow is projected. This is the dial plate. Those marks are usually numbered lines, the hour lines, that show the hours of the day. As the day passes, the gnomon' shadow moves around the dial; the shadow falls on a new line every hour.
Our Science Week is coming; and as every year, we are going to work about sundials. We are going to learn about these instruments, how they work, different types of sundials. And the most important... you are going to build your own sundial. Don't worry; it's very easy. Here you have some sundials made by students last year.

But, in my opinion, it is important to know about sundials in Granada too. How many sundials are there in Granada? Where are they? What kind of sundial is every one of them? Answer these questions as comments. Please, and if you can, take photos of those sundials. Send them to me and I will include your images in our blog.
And now, a very difficult question: where is the sundial of the picture below?

Construcción de relojes solares. Incluye la descripción de los principales tipos de relojes de sol así como plantillas de los cuadrantes solares para relojes orientados.
Algunos modelos de relojes solares.
Relojes solares otras semanas de la ciencia del IES Zaidín Vergeles.
La sombra del tiempo. Relojes solares del IES Zaidín Vergeles en el diario Granada Hoy.
Son muchas las páginas web dedicadas a la gnomónica y a la construcción de relojes solares. Algunas de las más representativas son:
Relojes de Sol de Mallorca.
Reloj andalusí. Web andaluza de relojes solares.
Relojes de Sol de la provincia de Málaga.
Asociación Amigos de los relojes de Sol.
North America Sundials Society.
Sundials on the Internet.

lunes, 13 de febrero de 2017

Life in a drop of water

A drop of untreated water is a very small world. Hundreds of small microorganisms like protozoans, bacteria and algae live there. We have colected different samples of water; in the laboratory we have deposited drops of water onto a glass slide, we have covered it with a cover slip and observed with a microscopy. There are lots of different small organisms living there. Here you have some pictures taken in our laboratory. We have observed protozoans like Paramecium or Vorticella, algae, even small pluricelular animals as rotifers, also known as wheel animals. We have found some parasite eggs too! 
What do you think about our experience? Try to draw one of these small organisms; I will publish the best drawings in our blog.

Parasite egg.
And here we have some of your drawings:

A Rotifer. Ainhoa Yolanda Monero Duperón, 1º ESO B.

A rotifer watched with a Foldscope. Ignacio Mengíbar, 1º ESO C

lunes, 9 de enero de 2017

Does acid rain affect leaves?

Finally, we have study the effect of acid rain on plant leaves. So, we have observed if there is any difference in leaves aspect in plants irrigated with acid solution. The results are in the following images. Can you see damaged leaves in the pictures? Can you describe differences between these two plants?

Leaves after acid rain treatment.
Leaves of plants irrigated with water,

The following pictures have been taken with a  magnifiying glass. So you can watch the difference in a better way.

Leaf treated with a solution of acetic acid 0,1%.
Leaf treated with water.

Acid rain and plants growth

We had six plates used as controls with germinated lentil seeds. Three of them have been irrigated with a solution of acetic acid 1%. The rest have been irrigated with water; these are now our control plates. The results are shown in these two pictures. You can see the difference in growth after some days of treatment.

Small lentil plants watered with acid rain.
Small lentil plants watered with water.

We had grown lentil seeds in pots. Half of them were watered with water and the rest with a simulated acid rain (acetic acid 1%). Nine days later we studied the growth of the plants. In this photo you can see both groups of plants.

Plants growth. Irrigated with water (left) and acetic acid solution 1% (right).
We want to study of acid rain affect the growth of plants; so, we had planted lentil seeds and we have measured the length of stems and roots in plants nine days later. The results are in the following tables. The first one shows the results in plants irrigated with acetic rain. The second one shows the results of the control set, irrigated with water.

Plants growth with acid rain

Plants growth irrigated with water.

What do you think about the influence of acid rain on the growth of plants? Are there differences between plants trated with water and with acid solution? How does acid rain affect plants growth? Please, write your answers as comments.

Acid rain and plants germination; final results.

These are the final results of our experiment about the effect of acid rain on the germination of lentil seeds. We have tested low concentrantions of acetic acid and only with acetic acid 0,1% we have obtained positive results. However the proportion of germinated seeds is lower than in seeds germinated only with water. In the next table you have the data.

Please, study the result of our experiments and write your conclusions.