Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 322 · 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 a child can do? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) letting the paper dry
2. 2.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
3. 3.🔍 Which is the odd one out? (a) writing the message (b) ironing the paper (c) reading the message (d) letting the paper dry
4. 4.True or false: letting the paper dry is a job a child can do. (a) False (b) True
5. 5.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a battery cell (c) a balloon (d) a cotton bud
6. 6.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) dry juice is see-through (d) the paper ate it
7. 7.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
8. 8.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
9. 9.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
10. 10.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a mirror (c) an adult with an iron (d) a small bowl
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a battery cell (d) a small bowl
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we measure it (c) we keep it the same
13. 13.⚖️ 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
14. 14.🛟 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
15. 15.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a magnet (c) lemon juice (d) an adult with an iron
17. 17.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
18. 18.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) physical (d) chemical
19. 19.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a cotton bud (d) a balloon
21. 21.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) putting the iron away (d) writing the message
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) a cotton bud (c) an adult with an iron (d) white paper
24. 24.True or false: ironing the paper is a job for an adult. (a) False (b) True
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) a magnet (d) lemon juice
26. 26.⚖️ 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) the kind of juice (c) the iron setting (d) how dark the writing is
27. 27.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) the paper floats (d) writing stays faint
28. 28.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) blue (c) white (d) green
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the kind of juice (c) how dark the writing is (d) the same cotton bud
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) an adult with an iron (c) a small bowl (d) a balloon
31. 31.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) turmeric powder (c) lemon juice (d) yeast
32. 32.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) lemon juice (c) turmeric powder (d) a cotton bud
33. 33.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
34. 34.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
35. 35.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if cooled (c) yes, if shaken (d) yes, in the dark
36. 36.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
37. 37.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
38. 38.True or false: ironing the paper is a job a child can do. (a) True (b) False
39. 39.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
40. 40.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a mirror (c) a battery cell (d) a balloon

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