Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 663 · 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 magnet for the secret lemon message? (a) not needed (b) needed
2. 2.🍋 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
3. 3.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
4. 4.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) letting the paper dry (c) writing the message (d) dipping the cotton bud
5. 5.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) any child (d) only an adult
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we change it (c) we keep it the same
7. 7.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it is magnetic (d) it can burn skin
8. 8.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a mirror (c) white paper (d) yeast
9. 9.🔍 Which is the odd one out? (a) cutting the lemon (b) letting the paper dry (c) putting the iron away (d) ironing the paper
10. 10.⚖️ 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) True (b) False
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we change it (c) we keep it the same
12. 12.🍋 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
13. 13.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) wash your hands (c) skip washing (d) rub your eyes
14. 14.🔮 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
15. 15.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) lemon juice (c) a battery cell (d) a magnet
16. 16.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) dipping the cotton bud (d) ironing the paper
17. 17.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) magnetic (c) chemical (d) physical
18. 18.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) cutting the lemon (d) putting the iron away
19. 19.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) yeast (d) a cotton bud
21. 21.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
22. 22.True or false: letting the paper dry is a job a child can do. (a) True (b) False
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) how dark the writing is (c) the same cotton bud (d) the ironing time
24. 24.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) dipping the cotton bud (d) putting the iron away
25. 25.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown
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) the same cotton bud
27. 27.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) False (b) True
29. 29.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) white (d) brown
30. 30.⚖️ 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 keep it the same (c) we measure it
31. 31.True or false: writing the message is a job for an adult. (a) False (b) True
32. 32.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) a mirror (c) a balloon (d) a battery cell
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we measure it (c) we keep it the same
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) a small bowl (d) turmeric powder
35. 35.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
36. 36.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
38. 38.True or false: plugging in the iron is a job for an adult. (a) False (b) True
39. 39.⚖️ 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
40. 40.True or false: yeast is needed for the secret lemon message. (a) True (b) False

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