Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 579 · 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.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) letting the paper dry (d) ironing the paper
2. 2.🔍 Which is the odd one out? (a) letting the paper dry (b) putting the iron away (c) reading the message (d) writing the message
3. 3.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) white paper (c) a mirror (d) a battery cell
4. 4.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) any child (d) the youngest child
5. 5.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) brown (d) white
6. 6.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) letting the paper dry (d) plugging in the iron
7. 7.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) it turned into air (d) dry juice is see-through
8. 8.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) it gets darker (c) the paper floats (d) writing turns green
9. 9.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we change it (c) we measure it
11. 11.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
12. 12.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
13. 13.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) physical (c) musical (d) magnetic
14. 14.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) white paper (c) lemon juice (d) a small bowl
15. 15.True or false: putting the iron away is a job for an adult. (a) True (b) False
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) an adult with an iron (c) a battery cell (d) lemon juice
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the ironing time (c) the kind of juice
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) False (b) True
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) a small bowl (c) a cotton bud (d) lemon juice
20. 20.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) almost nothing (c) blue words (d) a rainbow
21. 21.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we change it (c) we measure it
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) an adult with an iron (d) a balloon
24. 24.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
25. 25.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
28. 28.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is magnetic (d) it is sticky
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) lemon juice (d) a mirror
30. 30.🔍 Which is the odd one out? (a) dipping the cotton bud (b) ironing the paper (c) cutting the lemon (d) plugging in the iron
31. 31.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
32. 32.True or false: plugging in the iron is a job for an adult. (a) True (b) False
33. 33.True or false: plugging in the iron is a job a child can do. (a) False (b) True
34. 34.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) plugging in the iron (d) letting the paper dry
35. 35.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) turmeric powder (c) a mirror (d) a small bowl
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) the kind of juice (c) the same paper (d) how dark the writing is
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
38. 38.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) dipping the cotton bud (d) cutting the lemon
39. 39.True or false: reading the message is a job for an adult. (a) True (b) False
40. 40.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False

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