Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 410 · 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.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the kind of juice (c) the same paper (d) the iron setting
2. 2.True or false: reading the message is a job a child can do. (a) False (b) True
3. 3.⚖️ 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 same paper (c) the kind of juice
4. 4.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) it turned into air (d) dry juice is see-through
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) how dark the writing is (c) the same cotton bud (d) the iron setting
6. 6.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
7. 7.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
8. 8.⚖️ 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
9. 9.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) the youngest child (d) whoever is fastest
10. 10.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
11. 11.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it can burn skin (c) it is sticky (d) it is cold
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) white paper (c) a cotton bud (d) lemon juice
13. 13.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing stays faint (d) writing turns green
14. 14.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a magnet (c) a cotton bud (d) a battery cell
15. 15.🔍 Which is the odd one out? (a) plugging in the iron (b) writing the message (c) cutting the lemon (d) ironing the paper
16. 16.⚖️ 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
17. 17.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
18. 18.True or false: cutting the lemon is a job for an adult. (a) False (b) True
19. 19.🔍 Which is the odd one out? (a) cutting the lemon (b) dipping the cotton bud (c) writing the message (d) reading the message
20. 20.⚖️ 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
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
22. 22.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
23. 23.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a battery cell (c) a mirror (d) white paper
24. 24.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
25. 25.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) an adult with an iron (c) a balloon (d) a magnet
26. 26.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) turmeric powder (c) a small bowl (d) a battery cell
27. 27.🔍 Which is the odd one out? (a) ironing the paper (b) dipping the cotton bud (c) writing the message (d) reading the message
28. 28.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) writing the message (c) letting the paper dry (d) dipping the cotton bud
29. 29.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
30. 30.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) letting the paper dry (d) plugging in the iron
31. 31.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
32. 32.🧺 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) lemon juice (d) yeast
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we change it (c) we measure it
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a small bowl (d) a balloon
35. 35.True or false: putting the iron away is a job a child can do. (a) False (b) True
36. 36.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
37. 37.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) yeast (c) lemon juice (d) a magnet
38. 38.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) chemical (d) physical
39. 39.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
40. 40.⚖️ 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

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