Joseph Rollinson

Work

DuoCon 2020 - Our Efficacy Study

26 Sep 2020

Every year, Duolingo hosts a convention where we share new features and host guest speakers. This year, I presented our recent work on measuring the effectiveness of Duolingo, including our 2020 Efficacy Study.

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How Well Does Duolingo Work?

19 Aug 2020

In this study we found that Duolingo users who completed 5 sections of our French and Spanish courses for English speakers performed as well as university students who completed 4 semesters of university language instruction on reading and listening proficiency tests. Read the blog post or dive into the... </div>

NCME: Learning Assessment & User Behavior

28 Jul 2020

At this joint NCME conference panel with learning scientists from Khan Academy and Digital Promise, we share our approach to measuring learning in a data driven company culture.

Doing our homework: Checking in on how well we're teaching

31 Jan 2020

In another Duolingo blog post, we discuss our current approach to measuring learning inside the app.

Crown Levels: A Royal Redesign

11 Jul 2018

In this Duolingo blog post, I discuss a major change to the Duolingo user experience that allowed us to show harder content to our users while increasing engagement.

CMU Undergraduate Senior Thesis

01 May 2015

Paper Poster Presentation

Abstract

Intelligent tutoring systems provide their students with an adaptive personalized learning experience. To do so, intelligent tutoring systems attempt to capture the state of their students through a student model. Student models have two primary uses: prediction of future student performance and... </div>

From Predictive Models to Instructional Policies

01 Mar 2015

PDF Slides

Abstract

At their core, Intelligent Tutoring Systems consist of a student model and a policy. The student model captures the state of the student, and the policy uses the student model to individualize instruction. Different policies require different properties from the student model. For example,... </div>

Distance Sensor Interface

11 Dec 2011

The distance sensor interface is a set of distance sensors connected to an arduino, which is then connected via a serial connection to a computer. The computer has python modules that allow it to calibrate and collect data from the sensors. This interface uses GP2D02 sensors. These sensors have four... </div>

An Arduino Sensor Harp

11 Dec 2011

This project uses the sensor interface that was built previously.

This project uses two modules to create very different sounds: winsound and pyo. Winsound comes with python on windows machines, and pyo can be found on Google Code. This project... </div>

Using the GP2D02

11 Dec 2011

The GP2D02 library allows for simple communication between an arduino and one or multiple Sharp GP2D02 sensor. This library is available to download here.

The GP2D02 is a digital sensor with four connections. In this photo:

Sensor Front

  • The black wire is ground.
  • The green wire... </div>