Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 132 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
2. 2.True or false: cutting the lemon is a job a child can do. (a) True (b) False
3. 3.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) cutting the lemon (d) dipping the cotton bud
4. 4.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
5. 5.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) dipping the cotton bud (d) ironing the paper
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) a magnet (d) lemon juice
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we measure it (c) we keep it the same
8. 8.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) a mirror (d) white paper
10. 10.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
11. 11.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) physical (d) chemical
12. 12.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
13. 13.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
14. 14.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) False (b) True
16. 16.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
17. 17.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) writing stays faint (d) it gets darker
18. 18.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) the ink is magnetic (d) dry juice is see-through
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) the kind of juice (c) how dark the writing is
20. 20.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we keep it the same (c) we change it
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
23. 23.True or false: yeast is needed for the secret lemon message. (a) False (b) True
24. 24.🔍 Which is the odd one out? (a) writing the message (b) plugging in the iron (c) cutting the lemon (d) ironing the paper
25. 25.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) lick your fingers (c) skip washing (d) rub your eyes
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we change it (c) we measure it
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the ironing time (c) how dark the writing is (d) the kind of juice
29. 29.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) writing the message (c) dipping the cotton bud (d) letting the paper dry
30. 30.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) reading the message (d) cutting the lemon
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) white paper (c) a small bowl (d) lemon juice
32. 32.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
33. 33.True or false: plugging in the iron is a job for an adult. (a) False (b) True
34. 34.True or false: putting the iron away is a job for an adult. (a) True (b) False
35. 35.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
36. 36.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we keep it the same (c) we change it
38. 38.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
39. 39.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is magnetic (d) it is cold
40. 40.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) letting the paper dry (d) reading the message

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