The experiment circuit diagram of measuring resistance by physical voltammetry in the third grade of junior high school?

The experiment circuit diagram of measuring resistance by physical voltammetry in the third grade of junior high school?

This is the experimental circuit diagram of measuring resistance by voltammetry;
&The experimental principle is as follows
I=U/R R=U/I
Steps:
1. Disconnect the switch and connect the circuit according to the circuit diagram
2. Adjust the slide of the sliding rheostat to the maximum resistance and close the switch
3. Properly adjust the position of slide vane of sliding rheostat and record the reading of corresponding voltmeter & nbsp; U1 and ammeter & nbsp; I1 respectively
4. Then adjust the slide position of the sliding rheostat properly, and record the corresponding voltage representation U2 and current representation I2
5. Repeat steps 3 and 4 to record the corresponding voltage indication U3 and current indication I3 respectively
Experimental record form and data processing
Experiment times & nbsp; & nbsp; & nbsp; & nbsp; U / V & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; I / A & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; R / EU & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; average R
   1          U1      I1      R1
   2          U2      I2      R2     R=(R1+R2+R3)/3
   3          U3      I3      R3