Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 173 · 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 a battery cell for the secret lemon message? (a) not needed (b) needed
2. 2.True or false: writing the message is a job for an adult. (a) False (b) True
3. 3.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
4. 4.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) dry juice is see-through (d) the ink is magnetic
5. 5.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) musical (d) chemical
6. 6.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
7. 7.⚖️ 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
8. 8.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) writing the message (d) ironing the paper
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) how dark the writing is (c) the kind of juice (d) the same cotton bud
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) an adult with an iron (d) a balloon
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same cotton bud (b) the kind of juice (c) how dark the writing is
12. 12.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) ironing the paper (d) letting the paper dry
13. 13.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
14. 14.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) a rainbow (d) almost nothing
15. 15.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) any child (c) whoever is fastest (d) the youngest child
16. 16.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
17. 17.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) dipping the cotton bud (d) ironing the paper
18. 18.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a mirror (c) a magnet (d) a small bowl
19. 19.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) how dark the writing is (c) the kind of juice
21. 21.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it can burn skin (d) it is magnetic
22. 22.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) turmeric powder (c) lemon juice (d) a magnet
23. 23.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) letting the paper dry
24. 24.🍋 Which of these steps is a job for an adult? (a) writing the message (b) putting the iron away (c) reading the message (d) letting the paper dry
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the same paper (c) the iron setting (d) the same cotton bud
26. 26.⚖️ 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
27. 27.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
28. 28.⚖️ 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
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) an adult with an iron (c) a small bowl (d) lemon juice
30. 30.True or false: ironing the paper is a job a child can do. (a) False (b) True
31. 31.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) True (b) False
33. 33.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
34. 34.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) writing the message (c) ironing the paper (d) plugging in the iron
35. 35.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
36. 36.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) cutting the lemon (d) reading the message
37. 37.⚖️ 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 change it (c) we keep it the same
38. 38.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) dipping the cotton bud (d) plugging in the iron
39. 39.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
40. 40.True or false: a balloon is needed for the secret lemon message. (a) True (b) False

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