diff --git a/README.md b/README.md
index ca02309..0aab9b7 100644
--- a/README.md
+++ b/README.md
@@ -5,6 +5,8 @@
 This project contains **pytudes**—Python programs for perfecting programming skills. 
 
 Some are in Jupyter (IPython) notebooks, some in *.py files.
+
+[![Binder](https://mybinder.org/badge.svg)](https://mybinder.org/v2/gh/norvig/pytudes/master)
  
 # pytudes: Index of Jupyter (IPython) Notebooks
 
diff --git a/requirements.txt b/requirements.txt
new file mode 100644
index 0000000..24ce15a
--- /dev/null
+++ b/requirements.txt
@@ -0,0 +1 @@
+numpy