Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 124 · 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.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) it turned into air (c) the paper ate it (d) the ink is magnetic
2. 2.⚖️ 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
3. 3.True or false: ironing the paper is a job a child can do. (a) False (b) True
4. 4.True or false: writing the message is a job for an adult. (a) False (b) True
5. 5.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
6. 6.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) green (c) blue (d) brown
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.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) writing stays faint (d) it gets darker
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a balloon (c) lemon juice (d) an adult with an iron
10. 10.⚖️ 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 ironing time (c) the kind of juice (d) the same paper
11. 11.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
12. 12.True or false: reading the message is a job for an adult. (a) False (b) True
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we change it (c) we keep it the same
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
15. 15.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) only an adult (d) the youngest child
16. 16.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) plugging in the iron (d) writing the message
17. 17.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we measure it (c) we keep it the same
19. 19.⚖️ 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
20. 20.⚖️ 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
21. 21.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) skip washing (c) lick your fingers (d) rub your eyes
22. 22.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) writing the message (d) cutting the lemon
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) turmeric powder (c) a cotton bud (d) an adult with an iron
24. 24.True or false: cutting the lemon is a job a child can do. (a) False (b) True
25. 25.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
26. 26.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) reading the message (d) writing the message
27. 27.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) musical (c) magnetic (d) physical
28. 28.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
29. 29.⚖️ 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) False (b) True
30. 30.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) letting the paper dry
31. 31.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) yeast (c) lemon juice (d) a cotton bud
33. 33.🔍 Which is the odd one out? (a) ironing the paper (b) letting the paper dry (c) dipping the cotton bud (d) reading the message
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
35. 35.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
36. 36.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) putting the iron away (d) reading the message
37. 37.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
38. 38.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it is cold (d) it can burn skin
39. 39.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) writing the message (d) cutting the lemon
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) an adult with an iron (d) a battery cell

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