Arc & Angles in Circles Activity

So we are currently in our circles unit in Geometry.  We started this semester with the basic definitions related to circles, and for the past week and a half we have been working with the relationships between the arcs and angles created by intersecting diameters, chords, secants, and tangents.  Getting the kids to recognize the relationship and figure an arc or angle measure when there is only one thing going on isn't too bad, but when the figures get more complicated and there are multiple segments and lines intersecting in various places things get a whole lot more difficult.  We spent some time working on these types of figures this week and I found that being able to mark on a figure, erase, then mark again was helpful for many of my students, so I designed an activity that allowed them to do this.

I separated my students into groups of four and each group got a supply basket with dry erase markers and erasers (washcloths), as well as four copies of each of three figures.  The copies of these figures were each in a page protector.   Also in their supply baskets they got a page protector with multiple copies of the answer document.

Each student got a copy of the answer document, and they could choose which of the three figures they wanted to start with.  The figures were all in page protectors so students could mark on them with the dry erase markers as they figured various angle and arc measurements about the circle and their answers for specific arc and angle measures were recorded on the answer documents.  My students seemed to like being able to draw on the figures and erase things easily if they made a mistake or no longer needed a specific piece of information.  I also heard a lot of great math conversations as I circulated about the room checking on progress and answering questions.  Any activity that sparks good math discussion is a winner in my book.

Here are the figures that I had my students working with.

FIGURE 1

FIGURE 2

FIGURE 3

Answer Document
Note:  I had students add in the arc markings on the questions asking for arc measures.  

 When attempting an activity like this I highly recommend having group supply baskets pre-made.  I invested in a half a dozen shower caddies from Dollar Tree a couple years ago and they have been great to have for any kind of group project that requires supplies.  Sorting into the baskets is easy and they keep the kids from wandering the classroom in search of things they need. Clean up at the end of each period is also easy as the students just need to put everything back into the basket at each group of desks.