# Day 161: Circuits ILD Continued

The students started the hour by completing a formative assessment on determining the equivalent resistance of a circuit containing eight resistors.  Here it is:

It really was formative… nearly every student (well, maybe except 3 or 4 in each class) totally nailed it… no need to re-assess or re-teach. For those that need it, I posted some practice on Schoology.   Love formative assessment.

The remaining time was spent working on the Circuits ILD. We completed the circuit that asked the students to predict the size of the reading on 3 voltmeters across three resistors in series (R1=R2>R3).  Most groups predicted ΔV1>ΔV2>ΔV3, because of the order they appeared in the circuit.  A bit disappointing because we have worked on drawing electric potential diagrams.  Once the groups saw the results, they quickly realized that the location had nothing to do with the value… I’ll have to find a way next year to try to address this as we practice with the EPD’s… maybe just asking about changing the location of bulbs in Bulb Boy.

We also looked at parallel circuits:

This one was for the same two resistors that were wired in series in an earlier circuit.  I like this photo because it shows good the data is… just wish I had the circuit a bit more scrunched in so you could compare the brightness like the students did in class.  Speaking of students, here are two shots of the students preparing predictions:

Tomorrow we will work with three resistors in parallel and add the voltmeters back in.  I still have not given them the ‘official junction rule’ yet… they have only worked with two parallel circuits.  They have formed some ideas as to how parallel circuits behave and tomorrow we will do one more. or maybe two before we discuss and I let them throw the rule out to me.

General Physics:

They learned about resistances in series and parallel  and completed the same sample problem the advanced class did.  I like it when the generals do the same thing as the advanced… it gives them some confidence.