LM35 and 4-20 mA output
An op-amp driving the gate of a MOSFET with feedback from a resistor connected between the MOSFET Source and ground is the basis for a voltage-to-current converter. If the source resistor is 1k ohm, drain current 4-20 mA corresponds to 4-20 volts at the source (the gate takes no current). When your temperature sensor delivers a 75mV swing over the range of interest, you need the op-amp circuit to provide 21.3x inverting gain. Standard resistor values 10kohm (sensor to op-amp -ve input) and 220kohm (drain to op-amp -ve input) get you close. I leave as an exercise adding potentiometers for trimming exact gain and offset, and you need to look into minimising the input current offset error of the u741. By all means embrace the old u741 for school work because it is unconditionally stable in simple feedback circuits like this.