# Instruction Guide: How Fast?

This explicit science lesson takes the concepts learned in Moving Straight and ties in Middle School Science Standards on measuring, plotting and interpolating data.

Students should use the How Fast? Task Assignment sheet to complete this exploration.

Students use their program from Moving Straight to have their tribot move forward for 5 rotations and measure the time to do so at different power levels.

Students then complete the table to measure these times for a range of power levels and calculate the average time at each power level.

- Discuss with student how taking four measurements and calculating the average helps reduce random errors
- Note: Depending on tribot design, battery charge, etc., some tribots may not move (or move very slowly or erratically) at 10% power. Discuss why this could with students and then have them ignore this data point in their analysis

Students then plot this average data and use the plot to interpolate at time at an unmeasured power level. Student should validate this prediction by programming their tribot and measuring the time.

Discuss with Students the concept of Speed = Distance/Time. Have them measure the distance of 5 rotations (have them calculate it first, if you would like to spiral back to previous work) and use this value complete the Speed Table.

Students then plot this data and again interpolate/validate an intermediate value.

Finally students make predictions and reflect on what the have observed.

Note: if appropriate for the student's math skills, discuss the inverse nature of the two graphs. Time is of y = K/x form, while speed is the linear form of y = Kx