Week 2 - Investigating the viscosity of liquids.  

The thickness of a liquid is described as its viscosity. Some liquids are very runny and so are not very viscous, however others are very gloopy and thick. These liquids are said to be very viscous.

In the lesson we are going to investigate the order some liquids according to their viscosity.

When we plan an investigation, the first thing to think about is the variable which we will change. In this experiment we are comparing the viscosity of a number of liquids, so the liquid itself is what we are changing. We call this the independent variable. In the experiment below they test water, lamp oil, milk, rubbing alcohol, vegetable oil, maple syrup, washing up liquid, olive oil, corn syrup, and honey. Which one do you think is most viscous? Make a prediction now and write it down.

The next consideration when we plan our experiment is what do we need to measure to work out the answer to our question? We call this the dependent variable. Today we are going to measure the time a liquid takes to flow down a tray in seconds.

Finally the next stage when planning our investigation is to make sure all the other parts of the experiment stay the same for each liquid to make it fair. These are the control variables. In today's investigation it is important to use the same volume of liquid each time, to have the slope of the tray the same and also the same start and finish points.

Below is a video of a similar experiment to the one we are going to do in school. If you would like to do your own versions at home after you have watched this video you can but please check with an adult at home first to get permission.

Homework: Take a photo of 4 objects made of different materials with your iPad. Using pic collage name the material each object is made of and list at least 3 of its properties. Use the list of vocabulary from last week to help you. The vocabulary list is on Firefly in last weeks section. If you do not have access to the internet or have a problem with your i-pad, please complete the task on a piece of paper. If you want a template, you can print a sheet off below.