I completed my PTLLS micro-teach assessment yesterday; this involved teaching a 30-minute lesson with my peers as the students. I decided to choose a subject from my area of current teaching - the binary number system. I teach binary numbers to my 2nd years but had to make a few changes to the format to suit the PTLLS class.
I started the class by revising the decimal number system using an interactive group based task. The class was divided into four groups of 3; the task was to put in order four squares of paper: units, 10s, 100s, blank - the blank one was to be filled in as 1000s by the students. Secondly the students were asked to place counters (M&Ms) on the squares to represent the decimal number 3126. A discussion followed about decimal numbers: column (place) values, 0 - 9 symbols, etc.
I then asked the students what do they think the column values in base-2 would be, considering that base-10 column values were multiplied by 10 each time. Students deduced from the clue (base-2/base-10) the correct answer. I then asked how many symbols base-2 uses considering that base-10 uses 10 symbols. Again, the students deduced the correct answer.
Once the students knew the column values, and the number of symbols we could move on to conversions. I asked four volunteers to come to the front of the class and hold cards with 1 dot, 2 dots, 4 dots and 8 dots. The class then helped convert binary numbers into decimal by having the volunteers show their dots if there was a 1 in their column, and show the blank side if there was a 0 in their column. To convert from binary to decimal the students simply had to count the number of dots showing.
Students then swapped their cards with 4 other students and we did the opposite conversion - from decimal to binary - by making the number of dots add up to the desired number. Once students got the hang of this I gave them a worksheet to complete which asked them to convert a random decimal number to binary, swap worksheets with another student and try to decode their number back into decimal.
There was one main problem in the class - I didn't explain the worksheet clearly and it caused some confusion. This resulted in me having to explain to each group individually after they had already started completing the sheet. If the class was to be repeated I would explain the worksheet clearly and check the students understood before handing them out. It was also suggested that we do the example on the worksheet as a class.
Students completed the worksheet quicker than I thought and only a few required some help. Some students were initially anxious about taking a maths-based class (the students' backgrounds are varied: counsellor, beautician, artist, etc) but actually found that binary numbers were not hard at all and, by the end of the lesson, understood how to convert between binary & decimal numbers.
I ended the class with a quick note about binary and computers - how computers are made of switches with off representing 0 & on representing 1 - and a binary joke.
The students enjoyed the class and most of the feedback given was positive (with the exception of the worksheet explanation). The resources I used are available below.