Today I wanted to see what my class’s prior knowledge was around percent. Since they are 16-17 year olds they have been exposed to percent quite a lot. But since their math skills are operating anywhere between a grade 5 level through to a grade 9 level I wanted us all on the same page.
I started off with an Explain Everything file I put together. The slides start at a basic level but then creates a need to determine equivalent values that match a certain percentage.
Getting the explain everything file onto each students iPad, or getting them connected to the wifi, or showing them how to type in a URL can take some time…..so slide 1 is an easy intro that students who are waiting can work on.
I wanted to make sure that when we know the whole is 100 that just counting the tiles covered gives us the percentage. These were too easy for my students but it gave us some time to review writing a fraction as a decimal and as a percent. I asked students to tell me the percentage they covered and then we converted to a decimal and fraction. They had the option to record what they were thinking.
Right away almost all students covered 10 squares. I then asked them to convert their new fraction (10/50) into a decimal to see if we get 0.1 ….and then some shock on their faces appeared. Some students then knew their mistake and made some corrections. But we spent some time here going over the visual interpretation …..10% means that 10/100 are covered. This board had been cut in half so only 5 must be 10%.
— Jon Orr (@MrOrr_geek) September 10, 2016
This is where we generated a need for an algebraic (proportion) method. The students could estimate how tall he could be….but they had a hard time determining with accuracy how tall he would be. So this is where I stepped in and showed them how to calculate. The remaining slides with Fido and then with piles of gold and then finally with no visuals at all were to practice this method.
After all slides were finished they started on some more practice questions on paper. We’ll finish those tomorrow as most students just started it.
Grab a copy of the Explain Everything project file