The Arnold Arboretum of Harvard University

The Arboretum for Educators

Resources for Teachers, Students, and Families
 
October 2025
During the 2025–2026 school year the Arboretum for Educators will feature one native tree species per month, highlighting recognizable features and sharing interesting facts. This will be followed by Outdoor Journaling suggestions and related Science Labs. Embark on a yearlong tree investigation and outdoor journaling program: can you “collect” all 10 trees by June? Be sure to read the September newsletter about maples.

Mighty Oaks for Oaktober!

White oak
The national tree of the United States since 2004, the oak tree is a symbol of strength and endurance. There are over 500 species of oaks throughout the Northern Hemisphere and around 90 species in the US. A keystone species, oaks support more wildlife than any other native tree, providing food and shelter for invertebrates, insects, birds, and mammals alike. Want to identify oaks? Start by learning the two main groups of oak trees: white and red oaks.
White oak acorns and leaf
White oak (Quercus alba) leaves are arranged in a spiral around the twig and have rounded lobes. Their acorns are produced every year and germinate immediately upon falling onto moist ground. Once the deep root anchors the acorn it pauses development until spring, thereby preventing animals from eating the seed and getting a growth jumpstart in early spring. The white oak acorn top is bumpy and sits like a cap, rather than a hat, on the nut.
Red oak acorns and leaf
Red oaks (Quercus rubra) leaves have bristle tips on pointed lobes and produce acorns that take 2 years to develop. Mature acorns have a scaley top hat that often only covers the top quarter of the nut. Red oak acorns need to go through a cold spell (winter) before germinating, but because they have higher tannin content (bitter taste), animals tend to leave them alone.
Outdoor Journal Activities
  1. Oak leaves are perfect for leaf rubbings! Have children create leaf rubbings in their nature notebook and practice measuring length and width of the leaf blade and the petiole (leaf stalk), counting and recording the number of lobes, and describing color and texture of each.
  2. Document all the wildlife noticed in and around an oak tree. Look for evidence of insects on the leaves and bark; watch which birds use the oaks for shelter or nesting; observe squirrels and chipmunks that may come near; gently dig under the soil around the tree for more invertebrate presence. Use repeated visits to create a class list of species that depend on oaks to reinforce the concept of “keystone species.”
  3. Make a collection of acorns and play sorting games. Make subsets of acorn groups and have students “guess the rule”: acorns without caps, acorns with cracks, or acorns that are longer than they are wide, are all good ways to further observation skills.
A collection of 36 acorns
Science Labs
  1. Collect white oak acorns and germinate them indoors to create your own forest!
  2. Get outdoors and collect lots of acorns. Have students bring some in from their own yards or parks. Place a collection of acorns in a bucket of water and watch what happens. Ask the students to explain why some float and some sink. Cut open the floating acorns and observe the insides. Cut open the sinking acorns and make observations. Ask students to use what they have noticed to revise their earlier explanations.
  3. Use this Google slide show to learn more about acorns and weevils.

Arboretum Happenings

MassQ Ball 25

MassQ Ball: Color

Oct. 4
10-4pm
Bussey Street Gate

MassQ Ball 2025: Color is an intergenerational, cross-cultural celebration of the arts and culture of Boston’s many communities of color.
Learn More
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