LEGO Inspiration: Duplo Motorized Train


In LEGO Inspiration today, we will show you what we found interesting in the current LEGO DUPLO train sets.

Even though these LEGO DUPLO sets are “geared” (haha) more for ages 2-5, these trains have features that help the next generation to learn about robotics. We really like that sets like these help kids (that might not even be old enough yet for FIRST LEGO League) to consider different ways to use “blocks” to tell a robot what to do, as well as learn about sensors. Maybe these sets will get all kids, girls and boys, interested in robotics!

DUPLO is awesome for helping kids learn!

Even though LEGO DUPLO is more for ages 2-5, we still find things in the sets that will help kids learn about STEM concepts. For example there are DUPLO gears which teach young children how to gear up or down. There are 2 sizes of DUPLO gears, medium and small (one set that they appear in is Big Fair 10840).


Some of the DUPLO sets include slides which teach young learners about potential energy. Kids may not know those words yet, but they learn by doing and seeing how the ball or person speeds-up as they go down a slide. There are 2 different types of slides, straight (like in Emmet and Lucy’s Visitors from the DUPLO Planet 10895) and curved (which is a newer piece and appears in the Bedroom 10926 set and many others). The slides of the same type and different type can connect together!

slides connected…




The DUPLO train sets have “Action Bricks.” These are physical pieces of colored plastic that the train will drive over. The train “reads” which color is seen, and the colored action block the tells the train what to do.

Here is a yellow action brick in front of the train…


There are currently five different action bricks…


The different action bricks are the following (left to right): the red stop brick (which stops the train), the yellow sound brick (which makes the train use its horn), the green change direction brick (which changes what direction it’s going in, for example if it were going forward it would start going backward), the blue refuel brick (which “refuels” the train by stopping and making a liquid flowing sound before continuing), and the white light brick (which turns on/off the train’s light). We find it totally awesome that the train knows what brick it drives over by using a color sensor at the bottom! We use a color sensor with our EV3 all the time, but we never expected to find one on a LEGO DUPLO set!

color sensor on…


color sensor off…


These action bricks help kids understand color sensors at a young age! You might not think putting down an action brick is programming, but it is! The child is telling the train what to do by placing an “action brick” down. By placing the action bricks down in a certain order, the young LEGO fan is essentially writing a simple program for their train. This feature helps them get prepared for robotics and computer programming!

There is also a LEGO Education version of the DUPLO train; it is called the Coding Express 45025. The color sensor technology is the same for this train, but it is marketed at more of a school audience.

If you run out of the action bricks of a specific color, you can obviously buy more sets to get additional action bricks. You could also order specific ones through LEGO’s replacement bricks section of their website. However, the color sensor on the train is just looking for a specific color. This means that you can make your own “action bricks” using other LEGOs you may have lying around. For example, we used two 2×4 regular LEGO bricks of any color and attached them to smooth plates the color of action bricks. The entire DIY “action brick” we made was 12 long.

DIY action bricks…



We had fun making these of various colors, so that we could program our DUPLO train with a lot of actions.


The two retail train sets (Steam Train 10874 and Cargo Train 10875) already come with tracks to tell the train where to go, but LEGO also sells extension packs that come with different tracks. For example the the Train Tracks 10882 set comes with additional straight and curved tracks, 2 switch tracks that split the track in two (you can change which way you want the train to go), 2 stop tracks (that stop the train and end the track without an action brick), and a crossing track (that has barriers that can go up and down to let the cars through). The Train Bridge and Tracks 10872 set comes with regular tracks and a train bridge (the train can go on the bridge and under it).

Different tracks…


LEGO DUPLO train switch tracks are basically “if-then blocks” or “switch blocks”. For example, “if lever is pushed right, then turn left”. There are also switch blocks in EV3 programming, which use the same concept. For example, they can be used for something like “if left button is pressed, turn left, if not pressed, turn right” or something like “if the color sensor sees red, go forward or if it sees black, go backward.” The DUPLO switch tracks are basically the same thing as switch blocks, they both ask the same question “if”. This helps get young children ready for programming!

Switch tracks…


switch track pushed right…


switch track pushed left…


Believe it or not, putting down the tracks to tell the train where to go is also “programming.” In EV3 Mindstorms, we use blocks on the computer to tell the robot how to drive (in what direction and how far), but placing DUPLO tracks down to tell the DUPLO train to go in a circle or figure eight is not much different. For example, if you want to make your robot go forward and then turn 90° in EV3,o you would use a combination of move blocks, but with the DUPLO train you could use 1 straight track and 3 turn tracks, and the train and the robot would’ve done the same thing!

Track example…


Fun Learning!

The LEGO DUPLO train has a push and go motor, so if you push it, it will keep going (it can also do the same thing backwards). It is also fun putting figures in the passenger car and dropping them off at different destinations! These train sets help teach kids how to program, and get them familiar with color sensors. It helps them get prepared for robotics and is also fun at the same time. It is great seeing how concepts we use in the EV3 are being applied at even the preschool level with LEGO DUPLO sets. We sure had a lot of fun getting to play with these train sets!

We hope you enjoyed our article!

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